Auto merge of #66605 - GuillaumeGomez:drop-python2, r=Mark-Simulacrum

Stop explicitly depending on python 2

This PR revises our previous policy of officially only supporting and testing with python 2 in the CI environment to instead test with python 3. It also changes the defaults to python 3 in our various scripts (usually, by way of `python` rather than `python3` to preserve compatibility with systems that do not have a python 3 available).

The effect of this is that we expect all new patches to support python 3 (and will test as such). We explicitly also expect that patches support python 2.7 as well -- and test as such, though only on one builder. This is intended as a temporary, though likely long-lived, measure to preserve compatibility while looking towards the future which is likely to be a python 3 only world. We do not at this point set a timeline for when we'll drop support for python 2.7; it's plausible that this is months or years into the future, depending on how quickly the ecosystem drops support and how painful it is for us to maintain that support over time.

Closes #65063 (as far as I can tell; please file explicit and separate issues or PRs if not).

53 files changed, 108 insertions, 97 deletions

diff --git a/src/ci/docker/arm-android/Dockerfile b/src/ci/docker/arm-android/Dockerfile
index b934d1ce971..77514848167 100644
--- a/src/ci/docker/arm-android/Dockerfile
+++ b/src/ci/docker/arm-android/Dockerfile
@@ -31,7 +31,7 @@ ENV TARGETS=arm-linux-androideabi
 
 ENV RUST_CONFIGURE_ARGS --arm-linux-androideabi-ndk=/android/ndk/arm-14
 
-ENV SCRIPT python2.7 ../x.py test --target $TARGETS
+ENV SCRIPT python3 ../x.py test --target $TARGETS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/armhf-gnu/Dockerfile b/src/ci/docker/armhf-gnu/Dockerfile
index 5373612279b..d1bc70689e1 100644
--- a/src/ci/docker/armhf-gnu/Dockerfile
+++ b/src/ci/docker/armhf-gnu/Dockerfile
@@ -14,7 +14,7 @@ RUN apt-get update -y && apt-get install -y --no-install-recommends \
       libc6-dev \
       libc6-dev-armhf-cross \
       make \
-      python2.7 \
+      python3 \
       qemu-system-arm \
       xz-utils
 
@@ -78,6 +78,6 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --qemu-armhf-rootfs=/tmp/rootfs
-ENV SCRIPT python2.7 ../x.py test --target arm-unknown-linux-gnueabihf
+ENV SCRIPT python3 ../x.py test --target arm-unknown-linux-gnueabihf
 
 ENV NO_CHANGE_USER=1
diff --git a/src/ci/docker/disabled/aarch64-gnu/Dockerfile b/src/ci/docker/disabled/aarch64-gnu/Dockerfile
index b2a3ba3ec26..9dd0435ac4f 100644
--- a/src/ci/docker/disabled/aarch64-gnu/Dockerfile
+++ b/src/ci/docker/disabled/aarch64-gnu/Dockerfile
@@ -14,7 +14,7 @@ RUN apt-get update -y && apt-get install -y --no-install-recommends \
       libc6-dev \
       libc6-dev-arm64-cross \
       make \
-      python2.7 \
+      python3 \
       qemu-system-aarch64 \
       xz-utils
 
@@ -75,5 +75,5 @@ RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS \
       --qemu-aarch64-rootfs=/tmp/rootfs
-ENV SCRIPT python2.7 ../x.py test --target aarch64-unknown-linux-gnu
+ENV SCRIPT python3 ../x.py test --target aarch64-unknown-linux-gnu
 ENV NO_CHANGE_USER=1
diff --git a/src/ci/docker/disabled/asmjs/Dockerfile b/src/ci/docker/disabled/asmjs/Dockerfile
index e27a2a529a8..3fa65511e94 100644
--- a/src/ci/docker/disabled/asmjs/Dockerfile
+++ b/src/ci/docker/disabled/asmjs/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python \
+  python3 \
   git \
   cmake \
   sudo \
@@ -33,7 +33,7 @@ ENV EMCC_CFLAGS=-O1
 # Emscripten installation is user-specific
 ENV NO_CHANGE_USER=1
 
-ENV SCRIPT python2.7 ../x.py test --target $TARGETS
+ENV SCRIPT python3 ../x.py test --target $TARGETS
 
 # This is almost identical to the wasm32-unknown-emscripten target, so
 # running with assertions again is not useful
diff --git a/src/ci/docker/disabled/dist-aarch64-android/Dockerfile b/src/ci/docker/disabled/dist-aarch64-android/Dockerfile
index a7903b6f425..dea445c295c 100644
--- a/src/ci/docker/disabled/dist-aarch64-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-aarch64-android/Dockerfile
@@ -19,7 +19,7 @@ ENV RUST_CONFIGURE_ARGS \
       --enable-extended \
       --enable-cargo-openssl-static
 
-ENV SCRIPT python2.7 ../x.py dist --target $HOSTS --host $HOSTS
+ENV SCRIPT python3 ../x.py dist --target $HOSTS --host $HOSTS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-armv7-android/Dockerfile b/src/ci/docker/disabled/dist-armv7-android/Dockerfile
index c02a5e5a095..7227c41ccca 100644
--- a/src/ci/docker/disabled/dist-armv7-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-armv7-android/Dockerfile
@@ -33,11 +33,11 @@ ENV RUST_CONFIGURE_ARGS \
 # build to finish we use --warn-unresolved-symbols. Note that the missing
 # symbols does not affect std, only the compiler (llvm) and cargo (openssl).
 ENV SCRIPT \
-  python2.7 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
+  python3 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
   (export RUSTFLAGS="\"-C link-arg=-Wl,--warn-unresolved-symbols\""; \
     rm /android/ndk/arm && \
     ln -s /android/ndk/arm-14 /android/ndk/arm && \
-    python2.7 ../x.py dist --host $HOSTS --target $HOSTS)
+    python3 ../x.py dist --host $HOSTS --target $HOSTS)
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-i686-android/Dockerfile b/src/ci/docker/disabled/dist-i686-android/Dockerfile
index 04e83a431c4..b74dcefa351 100644
--- a/src/ci/docker/disabled/dist-i686-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-i686-android/Dockerfile
@@ -33,11 +33,11 @@ ENV RUST_CONFIGURE_ARGS \
 # build to finish we use --warn-unresolved-symbols. Note that the missing
 # symbols does not affect std, only the compiler (llvm) and cargo (openssl).
 ENV SCRIPT \
-  python2.7 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
+  python3 ../x.py build src/llvm --host $HOSTS --target $HOSTS && \
   (export RUSTFLAGS="\"-C link-arg=-Wl,--warn-unresolved-symbols\""; \
     rm /android/ndk/x86 && \
     ln -s /android/ndk/x86-14 /android/ndk/x86 && \
-    python2.7 ../x.py dist --host $HOSTS --target $HOSTS)
+    python3 ../x.py dist --host $HOSTS --target $HOSTS)
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile b/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile
index 3227819dad5..19df9d6cf62 100644
--- a/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile
+++ b/src/ci/docker/disabled/dist-powerpcspe-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=powerpc-unknown-linux-gnuspe
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile b/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile
index 952c265a139..62d0bfc71b2 100644
--- a/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile
+++ b/src/ci/docker/disabled/dist-sparc64-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=sparc64-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/disabled/dist-x86_64-android/Dockerfile b/src/ci/docker/disabled/dist-x86_64-android/Dockerfile
index 937301864cd..d44779763e5 100644
--- a/src/ci/docker/disabled/dist-x86_64-android/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-android/Dockerfile
@@ -19,7 +19,7 @@ ENV RUST_CONFIGURE_ARGS \
       --enable-extended \
       --enable-cargo-openssl-static
 
-ENV SCRIPT python2.7 ../x.py dist --target $HOSTS --host $HOSTS
+ENV SCRIPT python3 ../x.py dist --target $HOSTS --host $HOSTS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile b/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile
index dbff9e32e13..5b7196c573c 100644
--- a/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-dragonfly/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -33,4 +33,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-dragonfly
 
 ENV RUST_CONFIGURE_ARGS --enable-extended
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile b/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile
index 440afd7c97f..5b65335bfe4 100644
--- a/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-haiku/Dockerfile
@@ -18,7 +18,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   make \
   nasm \
   pkg-config \
-  python2.7 \
+  python3 \
   sudo \
   texinfo \
   wget \
@@ -46,4 +46,4 @@ ENV RUST_CONFIGURE_ARGS --disable-jemalloc \
   --set=$TARGET.cc=x86_64-unknown-haiku-gcc \
   --set=$TARGET.cxx=x86_64-unknown-haiku-g++ \
   --set=$TARGET.llvm-config=/bin/llvm-config-haiku
-ENV SCRIPT python2.7 ../x.py dist --host=$HOST --target=$HOST
+ENV SCRIPT python3 ../x.py dist --host=$HOST --target=$HOST
diff --git a/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile b/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile
index 11a3acd68e3..7b53e73d700 100644
--- a/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile
+++ b/src/ci/docker/disabled/dist-x86_64-redox/Dockerfile
@@ -19,4 +19,4 @@ ENV \
     CXX_x86_64_unknown_redox=x86_64-unknown-redox-g++
 
 ENV RUST_CONFIGURE_ARGS --enable-extended
-ENV SCRIPT python2.7 ../x.py dist --target x86_64-unknown-redox
+ENV SCRIPT python3 ../x.py dist --target x86_64-unknown-redox
diff --git a/src/ci/docker/dist-aarch64-linux/Dockerfile b/src/ci/docker/dist-aarch64-linux/Dockerfile
index f5eb66ed714..37e81dffc06 100644
--- a/src/ci/docker/dist-aarch64-linux/Dockerfile
+++ b/src/ci/docker/dist-aarch64-linux/Dockerfile
@@ -36,4 +36,4 @@ ENV RUST_CONFIGURE_ARGS \
       --enable-extended \
       --enable-profiler \
       --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-android/Dockerfile b/src/ci/docker/dist-android/Dockerfile
index 64f31750dd7..6d38e199564 100644
--- a/src/ci/docker/dist-android/Dockerfile
+++ b/src/ci/docker/dist-android/Dockerfile
@@ -32,7 +32,7 @@ ENV RUST_CONFIGURE_ARGS \
       --x86_64-linux-android-ndk=/android/ndk/x86_64-21 \
       --disable-docs
 
-ENV SCRIPT python2.7 ../x.py dist --target $TARGETS
+ENV SCRIPT python3 ../x.py dist --target $TARGETS
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
diff --git a/src/ci/docker/dist-arm-linux/Dockerfile b/src/ci/docker/dist-arm-linux/Dockerfile
index 50f7ca74e54..78f2734ed40 100644
--- a/src/ci/docker/dist-arm-linux/Dockerfile
+++ b/src/ci/docker/dist-arm-linux/Dockerfile
@@ -28,4 +28,4 @@ ENV CC_arm_unknown_linux_gnueabi=arm-unknown-linux-gnueabi-gcc \
 ENV HOSTS=arm-unknown-linux-gnueabi
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-armhf-linux/Dockerfile b/src/ci/docker/dist-armhf-linux/Dockerfile
index 209b6c166eb..175dadfd303 100644
--- a/src/ci/docker/dist-armhf-linux/Dockerfile
+++ b/src/ci/docker/dist-armhf-linux/Dockerfile
@@ -28,4 +28,4 @@ ENV CC_arm_unknown_linux_gnueabihf=arm-unknown-linux-gnueabihf-gcc \
 ENV HOSTS=arm-unknown-linux-gnueabihf
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-armv7-linux/Dockerfile b/src/ci/docker/dist-armv7-linux/Dockerfile
index f42a2bd8122..faa2ce10606 100644
--- a/src/ci/docker/dist-armv7-linux/Dockerfile
+++ b/src/ci/docker/dist-armv7-linux/Dockerfile
@@ -28,4 +28,4 @@ ENV CC_armv7_unknown_linux_gnueabihf=armv7-unknown-linux-gnueabihf-gcc \
 ENV HOSTS=armv7-unknown-linux-gnueabihf
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile b/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile
index 61c363fbfd6..996fffeb871 100644
--- a/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile
+++ b/src/ci/docker/dist-i586-gnu-i586-i686-musl/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   xz-utils \
@@ -46,5 +46,5 @@ ENV CFLAGS_i586_unknown_linux_musl=-Wa,-mrelax-relocations=no
 ENV TARGETS=i586-unknown-linux-gnu,i686-unknown-linux-musl
 
 ENV SCRIPT \
-      python2.7 ../x.py test --target $TARGETS && \
-      python2.7 ../x.py dist --target $TARGETS,i586-unknown-linux-musl
+      python3 ../x.py test --target $TARGETS && \
+      python3 ../x.py dist --target $TARGETS,i586-unknown-linux-musl
diff --git a/src/ci/docker/dist-i686-freebsd/Dockerfile b/src/ci/docker/dist-i686-freebsd/Dockerfile
index 6f6a663a330..7978bb70869 100644
--- a/src/ci/docker/dist-i686-freebsd/Dockerfile
+++ b/src/ci/docker/dist-i686-freebsd/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -30,4 +30,4 @@ ENV \
 ENV HOSTS=i686-unknown-freebsd
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mips-linux/Dockerfile b/src/ci/docker/dist-mips-linux/Dockerfile
index 466def1f80f..57a7fc25b5c 100644
--- a/src/ci/docker/dist-mips-linux/Dockerfile
+++ b/src/ci/docker/dist-mips-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mips-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mips64-linux/Dockerfile b/src/ci/docker/dist-mips64-linux/Dockerfile
index 2205b733e99..63f1028e2be 100644
--- a/src/ci/docker/dist-mips64-linux/Dockerfile
+++ b/src/ci/docker/dist-mips64-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -22,4 +22,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mips64-unknown-linux-gnuabi64
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mips64el-linux/Dockerfile b/src/ci/docker/dist-mips64el-linux/Dockerfile
index f1d9dad46ea..a51edbc9c79 100644
--- a/src/ci/docker/dist-mips64el-linux/Dockerfile
+++ b/src/ci/docker/dist-mips64el-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mips64el-unknown-linux-gnuabi64
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-mipsel-linux/Dockerfile b/src/ci/docker/dist-mipsel-linux/Dockerfile
index ee73e29c76e..908cef90cef 100644
--- a/src/ci/docker/dist-mipsel-linux/Dockerfile
+++ b/src/ci/docker/dist-mipsel-linux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -22,4 +22,4 @@ RUN sh /scripts/sccache.sh
 ENV HOSTS=mipsel-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-powerpc-linux/Dockerfile b/src/ci/docker/dist-powerpc-linux/Dockerfile
index 8c052db1b0d..b8792b0c7fa 100644
--- a/src/ci/docker/dist-powerpc-linux/Dockerfile
+++ b/src/ci/docker/dist-powerpc-linux/Dockerfile
@@ -35,4 +35,4 @@ ENV \
 ENV HOSTS=powerpc-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-powerpc64-linux/Dockerfile b/src/ci/docker/dist-powerpc64-linux/Dockerfile
index bb30210c056..a790a143ac5 100644
--- a/src/ci/docker/dist-powerpc64-linux/Dockerfile
+++ b/src/ci/docker/dist-powerpc64-linux/Dockerfile
@@ -36,4 +36,4 @@ ENV \
 ENV HOSTS=powerpc64-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-powerpc64le-linux/Dockerfile b/src/ci/docker/dist-powerpc64le-linux/Dockerfile
index ee9e4550483..5c17bc321c1 100644
--- a/src/ci/docker/dist-powerpc64le-linux/Dockerfile
+++ b/src/ci/docker/dist-powerpc64le-linux/Dockerfile
@@ -33,4 +33,4 @@ ENV \
 ENV HOSTS=powerpc64le-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-s390x-linux/Dockerfile b/src/ci/docker/dist-s390x-linux/Dockerfile
index 7ba6fe643c2..76d29a471c3 100644
--- a/src/ci/docker/dist-s390x-linux/Dockerfile
+++ b/src/ci/docker/dist-s390x-linux/Dockerfile
@@ -35,4 +35,4 @@ ENV \
 ENV HOSTS=s390x-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-various-1/Dockerfile b/src/ci/docker/dist-various-1/Dockerfile
index 4ac5e23d683..35b598e20f0 100644
--- a/src/ci/docker/dist-various-1/Dockerfile
+++ b/src/ci/docker/dist-various-1/Dockerfile
@@ -18,7 +18,6 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
   python3 \
   git \
   cmake \
@@ -209,8 +208,8 @@ ENV RUST_CONFIGURE_ARGS \
       --disable-docs
 
 ENV SCRIPT \
-      python2.7 ../x.py test --target $RUN_MAKE_TARGETS src/test/run-make && \
-      python2.7 ../x.py dist --target $TARGETS
+      python3 ../x.py test --target $RUN_MAKE_TARGETS src/test/run-make && \
+      python3 ../x.py dist --target $TARGETS
 
 # sccache
 COPY scripts/sccache.sh /scripts/
diff --git a/src/ci/docker/dist-various-2/Dockerfile b/src/ci/docker/dist-various-2/Dockerfile
index 5bb5436bec5..5864b5ffab2 100644
--- a/src/ci/docker/dist-various-2/Dockerfile
+++ b/src/ci/docker/dist-various-2/Dockerfile
@@ -17,7 +17,7 @@ RUN apt-get update && apt-get build-dep -y clang llvm && apt-get install -y --no
   libmpfr-dev \
   ninja-build \
   nodejs \
-  python2.7-dev \
+  python3-dev \
   software-properties-common \
   unzip \
   # Needed for apt-key to work:
@@ -110,4 +110,4 @@ ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --disable-docs \
   --set target.wasm32-wasi.wasi-root=/wasm32-wasi \
   --musl-root-armv7=/musl-armv7
 
-ENV SCRIPT python2.7 ../x.py dist --target $TARGETS
+ENV SCRIPT python3 ../x.py dist --target $TARGETS
diff --git a/src/ci/docker/dist-x86_64-freebsd/Dockerfile b/src/ci/docker/dist-x86_64-freebsd/Dockerfile
index 698b81a92e9..12170a36614 100644
--- a/src/ci/docker/dist-x86_64-freebsd/Dockerfile
+++ b/src/ci/docker/dist-x86_64-freebsd/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -30,4 +30,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-freebsd
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/dist-x86_64-musl/Dockerfile b/src/ci/docker/dist-x86_64-musl/Dockerfile
index ffeb265e11b..c026506b106 100644
--- a/src/ci/docker/dist-x86_64-musl/Dockerfile
+++ b/src/ci/docker/dist-x86_64-musl/Dockerfile
@@ -7,7 +7,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   wget \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   xz-utils \
@@ -48,4 +48,4 @@ ENV CFLAGS_x86_64_unknown_linux_musl="-Wa,-mrelax-relocations=no -Wa,--compress-
     -Wl,--compress-debug-sections=none"
 
 # To run native tests replace `dist` below with `test`
-ENV SCRIPT python2.7 ../x.py dist --build $HOSTS
+ENV SCRIPT python3 ../x.py dist --build $HOSTS
diff --git a/src/ci/docker/dist-x86_64-netbsd/Dockerfile b/src/ci/docker/dist-x86_64-netbsd/Dockerfile
index 44b1aaa24b1..135bb33cef7 100644
--- a/src/ci/docker/dist-x86_64-netbsd/Dockerfile
+++ b/src/ci/docker/dist-x86_64-netbsd/Dockerfile
@@ -19,4 +19,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-netbsd
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/i686-gnu-nopt/Dockerfile b/src/ci/docker/i686-gnu-nopt/Dockerfile
index 517b59c38dc..c15b437e6d3 100644
--- a/src/ci/docker/i686-gnu-nopt/Dockerfile
+++ b/src/ci/docker/i686-gnu-nopt/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -18,7 +18,7 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests
-ENV SCRIPT python2.7 ../x.py test
+ENV SCRIPT python3 ../x.py test
 
 # FIXME(#59637) takes too long on CI right now
 ENV NO_LLVM_ASSERTIONS=1 NO_DEBUG_ASSERTIONS=1
diff --git a/src/ci/docker/i686-gnu/Dockerfile b/src/ci/docker/i686-gnu/Dockerfile
index 03db3ba0995..377f07cef4e 100644
--- a/src/ci/docker/i686-gnu/Dockerfile
+++ b/src/ci/docker/i686-gnu/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -20,7 +20,7 @@ RUN sh /scripts/sccache.sh
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu
 # Exclude some tests that are unlikely to be platform specific, to speed up
 # this slow job.
-ENV SCRIPT python2.7 ../x.py test \
+ENV SCRIPT python3 ../x.py test \
   --exclude src/bootstrap \
   --exclude src/test/rustdoc-js \
   --exclude src/tools/error_index_generator \
diff --git a/src/ci/docker/mingw-check/Dockerfile b/src/ci/docker/mingw-check/Dockerfile
index 1293717f975..17d844a1f99 100644
--- a/src/ci/docker/mingw-check/Dockerfile
+++ b/src/ci/docker/mingw-check/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -22,9 +22,9 @@ RUN sh /scripts/sccache.sh
 COPY mingw-check/validate-toolstate.sh /scripts/
 
 ENV RUN_CHECK_WITH_PARALLEL_QUERIES 1
-ENV SCRIPT python2.7 ../x.py test src/tools/expand-yaml-anchors && \
-           python2.7 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \
-           python2.7 ../x.py build --stage 0 src/tools/build-manifest && \
-           python2.7 ../x.py test --stage 0 src/tools/compiletest && \
-           python2.7 ../x.py test src/tools/tidy && \
+ENV SCRIPT python3 ../x.py test src/tools/expand-yaml-anchors && \
+           python3 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \
+           python3 ../x.py build --stage 0 src/tools/build-manifest && \
+           python3 ../x.py test --stage 0 src/tools/compiletest && \
+           python3 ../x.py test src/tools/tidy && \
            /scripts/validate-toolstate.sh
diff --git a/src/ci/docker/mingw-check/validate-toolstate.sh b/src/ci/docker/mingw-check/validate-toolstate.sh
index 2ebf1d6d5ae..c6d728eb80d 100755
--- a/src/ci/docker/mingw-check/validate-toolstate.sh
+++ b/src/ci/docker/mingw-check/validate-toolstate.sh
@@ -7,12 +7,12 @@ IFS=$'\n\t'
 rm -rf rust-toolstate
 git clone --depth=1 https://github.com/rust-lang-nursery/rust-toolstate.git
 cd rust-toolstate
-python2.7 "../../src/tools/publish_toolstate.py" "$(git rev-parse HEAD)" \
+python3 "../../src/tools/publish_toolstate.py" "$(git rev-parse HEAD)" \
     "$(git log --format=%s -n1 HEAD)" "" ""
 # Only check maintainers if this build is supposed to publish toolstate.
 # Builds that are not supposed to publish don't have the access token.
 if [ -n "${TOOLSTATE_PUBLISH+is_set}" ]; then
-  TOOLSTATE_VALIDATE_MAINTAINERS_REPO=rust-lang/rust python2.7 \
+  TOOLSTATE_VALIDATE_MAINTAINERS_REPO=rust-lang/rust python3 \
       "../../src/tools/publish_toolstate.py"
 fi
 cd ..
diff --git a/src/ci/docker/scripts/android-base-apt-get.sh b/src/ci/docker/scripts/android-base-apt-get.sh
index 738410c58fc..391b68ea637 100644
--- a/src/ci/docker/scripts/android-base-apt-get.sh
+++ b/src/ci/docker/scripts/android-base-apt-get.sh
@@ -11,7 +11,7 @@ apt-get install -y --no-install-recommends \
   libssl-dev \
   make \
   pkg-config \
-  python2.7 \
+  python3 \
   sudo \
   unzip \
   xz-utils
diff --git a/src/ci/docker/scripts/android-ndk.sh b/src/ci/docker/scripts/android-ndk.sh
index 0db30e420e3..dafcb3cb7a7 100644
--- a/src/ci/docker/scripts/android-ndk.sh
+++ b/src/ci/docker/scripts/android-ndk.sh
@@ -13,7 +13,7 @@ download_ndk() {
 
 make_standalone_toolchain() {
     # See https://developer.android.com/ndk/guides/standalone_toolchain.htm
-    python2.7 /android/ndk/ndk/build/tools/make_standalone_toolchain.py \
+    python3 /android/ndk/ndk/build/tools/make_standalone_toolchain.py \
         --install-dir /android/ndk/$1-$2 \
         --arch $1 \
         --api $2
diff --git a/src/ci/docker/scripts/cross-apt-packages.sh b/src/ci/docker/scripts/cross-apt-packages.sh
index bb72e33def2..7030cd74cae 100644
--- a/src/ci/docker/scripts/cross-apt-packages.sh
+++ b/src/ci/docker/scripts/cross-apt-packages.sh
@@ -19,7 +19,7 @@ apt-get update && apt-get install -y --no-install-recommends \
   make \
   patch \
   pkg-config \
-  python2.7 \
+  python3 \
   sudo \
   texinfo \
   unzip \
diff --git a/src/ci/docker/test-various/Dockerfile b/src/ci/docker/test-various/Dockerfile
index 6a2600d8756..9276e4ed82d 100644
--- a/src/ci/docker/test-various/Dockerfile
+++ b/src/ci/docker/test-various/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python \
+  python3 \
   git \
   cmake \
   sudo \
@@ -40,7 +40,7 @@ ENV RUST_CONFIGURE_ARGS \
 ENV NO_DEBUG_ASSERTIONS=1
 
 ENV WASM_TARGETS=wasm32-unknown-unknown
-ENV WASM_SCRIPT python2.7 /checkout/x.py test --target $WASM_TARGETS \
+ENV WASM_SCRIPT python3 /checkout/x.py test --target $WASM_TARGETS \
   src/test/run-make \
   src/test/ui \
   src/test/compile-fail \
@@ -49,13 +49,13 @@ ENV WASM_SCRIPT python2.7 /checkout/x.py test --target $WASM_TARGETS \
   src/libcore
 
 ENV NVPTX_TARGETS=nvptx64-nvidia-cuda
-ENV NVPTX_SCRIPT python2.7 /checkout/x.py test --target $NVPTX_TARGETS \
+ENV NVPTX_SCRIPT python3 /checkout/x.py test --target $NVPTX_TARGETS \
   src/test/run-make \
   src/test/assembly
 
 ENV MUSL_TARGETS=x86_64-unknown-linux-musl \
     CC_x86_64_unknown_linux_musl=x86_64-linux-musl-gcc \
     CXX_x86_64_unknown_linux_musl=x86_64-linux-musl-g++
-ENV MUSL_SCRIPT python2.7 /checkout/x.py test --target $MUSL_TARGETS
+ENV MUSL_SCRIPT python3 /checkout/x.py test --target $MUSL_TARGETS
 
 ENV SCRIPT $WASM_SCRIPT && $NVPTX_SCRIPT && $MUSL_SCRIPT
diff --git a/src/ci/docker/wasm32/Dockerfile b/src/ci/docker/wasm32/Dockerfile
index a0f35afd995..91c492d03c1 100644
--- a/src/ci/docker/wasm32/Dockerfile
+++ b/src/ci/docker/wasm32/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python \
+  python3 \
   git \
   cmake \
   sudo \
@@ -20,6 +20,9 @@ RUN bash /scripts/emscripten.sh
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+# emcc seems to need python to specifically be "python" and not "python3"
+RUN ln `which python3` /usr/bin/python
+
 ENV PATH=$PATH:/emsdk-portable
 ENV PATH=$PATH:/emsdk-portable/upstream/emscripten/
 ENV PATH=$PATH:/emsdk-portable/node/12.9.1_64bit/bin/
@@ -35,7 +38,7 @@ ENV NO_CHANGE_USER=1
 
 # FIXME: Re-enable these tests once https://github.com/rust-lang/cargo/pull/7476
 # is picked up by CI
-ENV SCRIPT python2.7 ../x.py test --target $TARGETS \
+ENV SCRIPT python3 ../x.py test --target $TARGETS \
     --exclude src/libcore \
     --exclude src/liballoc \
     --exclude src/libproc_macro \
diff --git a/src/ci/docker/x86_64-gnu-aux/Dockerfile b/src/ci/docker/x86_64-gnu-aux/Dockerfile
index 44bee199911..86ac0256d28 100644
--- a/src/ci/docker/x86_64-gnu-aux/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-aux/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   libssl-dev \
diff --git a/src/ci/docker/x86_64-gnu-debug/Dockerfile b/src/ci/docker/x86_64-gnu-debug/Dockerfile
index 890e13232c3..c5e41b8a75a 100644
--- a/src/ci/docker/x86_64-gnu-debug/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-debug/Dockerfile
@@ -6,8 +6,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
-  python2.7-dev \
+  python3 \
+  python3-dev \
   libxml2-dev \
   libncurses-dev \
   libedit-dev \
@@ -40,5 +40,5 @@ ENV RUST_CONFIGURE_ARGS \
       --set target.x86_64-unknown-linux-gnu.cxx=clang++
 
 ENV SCRIPT \
-  python2.7 ../x.py build && \
-  python2.7 ../x.py test src/test/run-make-fulldeps --test-args clang
+  python3 ../x.py build && \
+  python3 ../x.py test src/test/run-make-fulldeps --test-args clang
diff --git a/src/ci/docker/x86_64-gnu-distcheck/Dockerfile b/src/ci/docker/x86_64-gnu-distcheck/Dockerfile
index 364f45aba2c..cc07a591cc1 100644
--- a/src/ci/docker/x86_64-gnu-distcheck/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-distcheck/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -19,7 +19,7 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu --set rust.ignore-git=false
-ENV SCRIPT python2.7 ../x.py test distcheck
+ENV SCRIPT python3 ../x.py test distcheck
 ENV DIST_SRC 1
 
 # The purpose of this builder is to test that we can `./x.py test` successfully
diff --git a/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile b/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile
index 207f972c3cd..de7ee6950b5 100644
--- a/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-full-bootstrap/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -21,7 +21,7 @@ RUN sh /scripts/sccache.sh
 ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
       --enable-full-bootstrap
-ENV SCRIPT python2.7 ../x.py build
+ENV SCRIPT python3 ../x.py build
 
 # In general this just slows down the build and we're just a smoke test that
 # a full bootstrap works in general, so there's not much need to take this
diff --git a/src/ci/docker/x86_64-gnu-nopt/Dockerfile b/src/ci/docker/x86_64-gnu-nopt/Dockerfile
index 6a5c7f5d9e6..096f67e13d1 100644
--- a/src/ci/docker/x86_64-gnu-nopt/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-nopt/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -21,4 +21,4 @@ RUN sh /scripts/sccache.sh
 ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu \
   --disable-optimize-tests \
   --set rust.test-compare-mode
-ENV SCRIPT python2.7 ../x.py test
+ENV SCRIPT python3 ../x.py test
diff --git a/src/ci/docker/x86_64-gnu-tools/Dockerfile b/src/ci/docker/x86_64-gnu-tools/Dockerfile
index 51193402ee8..148e09f6ad1 100644
--- a/src/ci/docker/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/x86_64-gnu-tools/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   libssl-dev \
diff --git a/src/ci/docker/x86_64-gnu-tools/checktools.sh b/src/ci/docker/x86_64-gnu-tools/checktools.sh
index 72325c7b948..00ac20c08dc 100755
--- a/src/ci/docker/x86_64-gnu-tools/checktools.sh
+++ b/src/ci/docker/x86_64-gnu-tools/checktools.sh
@@ -7,7 +7,7 @@ X_PY="$1"
 # Try to test all the tools and store the build/test success in the TOOLSTATE_FILE
 
 set +e
-python2.7 "$X_PY" test --no-fail-fast \
+python3 "$X_PY" test --no-fail-fast \
     src/doc/book \
     src/doc/nomicon \
     src/doc/reference \
@@ -22,4 +22,4 @@ python2.7 "$X_PY" test --no-fail-fast \
 
 set -e
 
-python2.7 "$X_PY" test check-tools
+python3 "$X_PY" test check-tools
diff --git a/src/ci/docker/x86_64-gnu/Dockerfile b/src/ci/docker/x86_64-gnu/Dockerfile
index b864c09ea8c..af6e1318062 100644
--- a/src/ci/docker/x86_64-gnu/Dockerfile
+++ b/src/ci/docker/x86_64-gnu/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
+  python3 \
   git \
   cmake \
   sudo \
@@ -23,4 +23,4 @@ ENV RUST_CONFIGURE_ARGS \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs
-ENV SCRIPT python2.7 ../x.py test
+ENV SCRIPT python3 ../x.py test
diff --git a/src/ci/run.sh b/src/ci/run.sh
index 73c3a964f53..59f2736cbd4 100755
--- a/src/ci/run.sh
+++ b/src/ci/run.sh
@@ -23,6 +23,14 @@ fi
 ci_dir=`cd $(dirname $0) && pwd`
 source "$ci_dir/shared.sh"
 
+if command -v python > /dev/null; then
+    PYTHON="python"
+elif command -v python3 > /dev/null; then
+    PYTHON="python3"
+else
+    PYTHON="python2"
+fi
+
 if ! isCI || isCiBranch auto || isCiBranch beta; then
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set build.print-step-timings --enable-verbose-tests"
 fi
@@ -107,7 +115,7 @@ SCCACHE_IDLE_TIMEOUT=10800 sccache --start-server || true
 
 if [ "$RUN_CHECK_WITH_PARALLEL_QUERIES" != "" ]; then
   $SRC/configure --enable-parallel-compiler
-  CARGO_INCREMENTAL=0 python2.7 ../x.py check
+  CARGO_INCREMENTAL=0 $PYTHON ../x.py check
   rm -f config.toml
   rm -rf build
 fi
diff --git a/src/ci/scripts/install-mingw.sh b/src/ci/scripts/install-mingw.sh
index 78728dd7d00..ae85d5cab01 100755
--- a/src/ci/scripts/install-mingw.sh
+++ b/src/ci/scripts/install-mingw.sh
@@ -50,8 +50,9 @@ if isWindows; then
     esac
 
     if [[ "${CUSTOM_MINGW-0}" -ne 1 ]]; then
-        pacman -S --noconfirm --needed mingw-w64-$arch-toolchain \
-            mingw-w64-$arch-cmake mingw-w64-$arch-gcc mingw-w64-$arch-python2
+        pacman -S --noconfirm --needed mingw-w64-$arch-toolchain mingw-w64-$arch-cmake \
+            mingw-w64-$arch-gcc \
+            mingw-w64-$arch-python # the python package is actually for python3
         ciCommandAddPath "$(ciCheckoutPath)/msys2/mingw${bits}/bin"
     else
         mingw_dir="mingw${bits}"
diff --git a/src/ci/scripts/install-msys2-packages.sh b/src/ci/scripts/install-msys2-packages.sh
index 22b9854ad5e..3874a86e120 100755
--- a/src/ci/scripts/install-msys2-packages.sh
+++ b/src/ci/scripts/install-msys2-packages.sh
@@ -13,7 +13,7 @@ if isWindows; then
     # one way or another. The msys interpreters seem to have weird path conversions
     # baked in which break LLVM's build system one way or another, so let's use the
     # native version which keeps everything as native as possible.
-    python_home="C:/hostedtoolcache/windows/Python/2.7.17/x64"
-    cp "${python_home}/python.exe" "${python_home}/python2.7.exe"
-    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\2.7.17\\x64"
+    python_home="C:/hostedtoolcache/windows/Python/3.7.6/x64"
+    cp "${python_home}/python.exe" "${python_home}/python3.exe"
+    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\3.7.6\\x64"
 fi