build: improve script and travis config

* fix a diff failure on windows

See https://travis-ci.com/rust-lang/rust-clippy/jobs/245971932#L1625
for an example.

* use cmp instead of diff > /dev/null

* clone single branch instead of clone then checking out

* do not decrypt key if have no diff change

1 files changed, 25 insertions, 30 deletions

diff --git a/.github/deploy.sh b/.github/deploy.sh
index a242c35c3ae..b8209159284 100755
--- a/.github/deploy.sh
+++ b/.github/deploy.sh
@@ -13,11 +13,7 @@ SSH_REPO=${REPO/https:\/\/github.com\//git@github.com:}
 SHA=$(git rev-parse --verify HEAD)
 
 # Clone the existing gh-pages for this repo into out/
-(
-    git clone "$REPO" out
-    cd out
-    git checkout $TARGET_BRANCH
-)
+git clone --quiet --single-branch --branch "$TARGET_BRANCH" "$REPO" out
 
 echo "Removing the current docs for master"
 rm -rf out/master/ || exit 0
@@ -27,7 +23,7 @@ mkdir out/master/
 cp util/gh-pages/index.html out/master
 python ./util/export.py out/master/lints.json
 
-if [ -n "$TRAVIS_TAG" ]; then
+if [[ -n "$TRAVIS_TAG" ]]; then
     echo "Save the doc for the current tag ($TRAVIS_TAG) and point current/ to it"
     cp -r out/master "out/$TRAVIS_TAG"
     rm -f out/current
@@ -35,27 +31,36 @@ if [ -n "$TRAVIS_TAG" ]; then
 fi
 
 # Generate version index that is shown as root index page
-(
-    cp util/gh-pages/versions.html out/index.html
-
-    cd out
-    python -c '\
-        import os, json;\
-        print json.dumps([\
-            dir for dir in os.listdir(".")\
-            if not dir.startswith(".") and os.path.isdir(dir)\
-        ])' > versions.json
-)
+cp util/gh-pages/versions.html out/index.html
+pushd out
+
+cat <<-EOF | python - > versions.json
+import os, json
+print json.dumps([
+    dir for dir in os.listdir(".") if not dir.startswith(".") and os.path.isdir(dir)
+])
+EOF
+popd
 
 # Pull requests and commits to other branches shouldn't try to deploy, just build to verify
-if [ "$TRAVIS_PULL_REQUEST" != "false" ] || [ "$TRAVIS_BRANCH" != "$SOURCE_BRANCH" ]; then
+if [[ "$TRAVIS_PULL_REQUEST" != "false" ]] || [[ "$TRAVIS_BRANCH" != "$SOURCE_BRANCH" ]]; then
     # Tags should deploy
-    if [ -z "$TRAVIS_TAG" ]; then
+    if [[ -z "$TRAVIS_TAG" ]]; then
         echo "Generated, won't push"
         exit 0
     fi
 fi
 
+# Now let's go have some fun with the cloned repo
+cd out
+git config user.name "Travis CI"
+git config user.email "travis@ci.invalid"
+
+if git diff --exit-code --quiet; then
+    echo "No changes to the output on this push; exiting."
+    exit 0
+fi
+
 # Get the deploy key by using Travis's stored variables to decrypt deploy_key.enc
 ENCRYPTION_LABEL=e3a2d77100be
 ENCRYPTED_KEY_VAR="encrypted_${ENCRYPTION_LABEL}_key"
@@ -64,19 +69,9 @@ ENCRYPTED_KEY=${!ENCRYPTED_KEY_VAR}
 ENCRYPTED_IV=${!ENCRYPTED_IV_VAR}
 openssl aes-256-cbc -K "$ENCRYPTED_KEY" -iv "$ENCRYPTED_IV" -in .github/deploy_key.enc -out .github/deploy_key -d
 chmod 600 .github/deploy_key
-eval $(ssh-agent -s)
+eval "$(ssh-agent -s)"
 ssh-add .github/deploy_key
 
-# Now let's go have some fun with the cloned repo
-cd out
-git config user.name "Travis CI"
-git config user.email "travis@ci.invalid"
-
-if [ -z "$(git diff --exit-code)" ]; then
-    echo "No changes to the output on this push; exiting."
-    exit 0
-fi
-
 git add .
 git commit -m "Automatic deploy to GitHub Pages: ${SHA}"