Add set -e and improve Travis config

Author: tesuji

.travis.yml

@@ -32,13 +32,12 @@ install:
       if ! rustup component add rustfmt; then
         cargo install -Z install-upgrade --git https://github.com/rust-lang/rustfmt --bin rustfmt
       fi
-      if [ "$TRAVIS_OS_NAME" == "linux" ]; then
+      if [[ "$TRAVIS_OS_NAME" == linux ]]; then
         . $HOME/.nvm/nvm.sh
         nvm install stable
         nvm use stable
         npm install remark-cli remark-lint
-      fi
-      if [ "$TRAVIS_OS_NAME" == "windows" ]; then
+      elif [[ "$TRAVIS_OS_NAME" == windows ]]; then
         choco install windows-sdk-10.1
       fi
     fi
@@ -102,32 +101,32 @@ matrix:
 
 before_script:
   - |
-    if [ "$TRAVIS_BRANCH" == "auto" ] || [ "$TRAVIS_BRANCH" == "try" ]; then
-      pr=$(echo $TRAVIS_COMMIT_MESSAGE | grep -o "#[0-9]*" | head -1 | sed 's/^#//g')
-      output=$(curl -H "Authorization: token $GITHUB_API_TOKEN" -s "https://api.github.com/repos/rust-lang/rust-clippy/pulls/$pr" | \
+    if [[ "$TRAVIS_BRANCH" == "auto" ]] || [[ "$TRAVIS_BRANCH" == "try" ]]; then
+      PR=$(echo "$TRAVIS_COMMIT_MESSAGE" | grep -o "#[0-9]*" | head -1 | sed 's/^#//g')
+      output=$(curl -H "Authorization: token $GITHUB_API_TOKEN" -s "https://api.github.com/repos/rust-lang/rust-clippy/pulls/$PR" | \
         python -c "import sys, json; print(json.load(sys.stdin)['body'])" | \
         grep "^changelog: " | \
         sed "s/changelog: //g")
-      if [ -z "$output" ]; then
+      if [[ -z "$output" ]]; then
         echo "ERROR: PR body must contain 'changelog: ...'"
         exit 1
-      elif [ "$output" = "none" ]; then
+      elif [[ "$output" = "none" ]]; then
         echo "WARNING: changelog is 'none'"
       fi
     fi
   - |
     rm rust-toolchain
     ./setup-toolchain.sh
   - |
-    if [ "$TRAVIS_OS_NAME" == "windows" ]; then
+    if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then
       export PATH=$PATH:$(rustc --print sysroot)/bin
     else
       export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib
     fi
 
 script:
   - |
-    if [ -z ${INTEGRATION} ]; then
+    if [[ -z ${INTEGRATION} ]]; then
       travis_wait 30 ./ci/base-tests.sh && sleep 5
     else
       ./ci/integration-tests.sh && sleep 5