Treat byte compilation warnings as test suite failures.

.travis.yml

@@ -7,13 +7,13 @@ before_install:
   - sudo add-apt-repository -y ppa:cassou/emacs
   - sudo add-apt-repository -y ppa:ubuntu-elisp/ppa
   - sudo apt-get update -y -q
-  - sudo apt-get install emacs23-nox emacs24-nox emacs-snapshot-nox
+  - sudo apt-get install $EMACS-nox
 install:
-  - $EMACS -Q -batch --eval '(setq byte-compile-error-on-warn t)' -f batch-byte-compile rainbow-delimiters.el
-script:
   - if [ "$EMACS" = "emacs23" ]; then
       curl -O 'https://raw.githubusercontent.com/ohler/ert/c619b56c5bc6a866e33787489545b87d79973205/lisp/emacs-lisp/ert.el';
     fi
+script:
+  - $EMACS -Q -batch --eval '(setq byte-compile-error-on-warn t)' -f batch-byte-compile rainbow-delimiters.el
   - $EMACS -Q -batch -l rainbow-delimiters-test.el -f ert-run-tests-batch-and-exit
 notifications:
   email: false