look for python2 symlinks before bootstrap python

Before this commit, if you're running x.py directly on a system where
`python` is symlinked to Python 3, then the `python` config option will
default to a Python 3 interpreter. This causes debuginfo tests to fail
with an opaque error message, since they have a hard requirement on
Python 2.

This commit modifies the Python probe behavior to look for python2.7 and
python2 *before* using the interpreter used to execute `x.py`.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 1a26309b471..b9f456e9100 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -109,9 +109,9 @@ pub fn check(build: &mut Build) {
     }
 
     build.config.python = build.config.python.take().map(|p| cmd_finder.must_have(p))
-        .or_else(|| env::var_os("BOOTSTRAP_PYTHON").map(PathBuf::from)) // set by bootstrap.py
         .or_else(|| cmd_finder.maybe_have("python2.7"))
         .or_else(|| cmd_finder.maybe_have("python2"))
+        .or_else(|| env::var_os("BOOTSTRAP_PYTHON").map(PathBuf::from)) // set by bootstrap.py
         .or_else(|| Some(cmd_finder.must_have("python")));
 
     build.config.nodejs = build.config.nodejs.take().map(|p| cmd_finder.must_have(p))