Travis: introduce $GEMDIR env var

.travis.yml

@@ -4,14 +4,15 @@ node_js:
 before_install:
   - time sudo pip install --use-mirrors -r test-infra/requirements.txt
   - rvm use 1.9.3 --fuzzy
-  - if [ "$TWBS_TEST" = validate-html ]; then echo "ruby=$(basename $(rvm gemdir)) jekyll=$JEKYLL_VERSION" > pseudo_Gemfile.lock; fi
+  - export GEMDIR=$(rvm gemdir)
+  - if [ "$TWBS_TEST" = validate-html ]; then echo "ruby=$(basename $GEMDIR) jekyll=$JEKYLL_VERSION" > pseudo_Gemfile.lock; fi
 install:
   - time npm install -g grunt-cli
   - ./test-infra/s3_cache.py download 'npm packages' test-infra/npm-shrinkwrap.canonical.json ./node_modules || time ./test-infra/uncached-npm-install.sh
-  - if [ "$TWBS_TEST" = validate-html ]; then ./test-infra/s3_cache.py download rubygems pseudo_Gemfile.lock $(rvm gemdir) || time gem install -N jekyll -v $JEKYLL_VERSION; fi
+  - if [ "$TWBS_TEST" = validate-html ]; then ./test-infra/s3_cache.py download rubygems pseudo_Gemfile.lock $GEMDIR || time gem install -N jekyll -v $JEKYLL_VERSION; fi
 after_script:
   - if [ "$TWBS_TEST" = core ]; then ./test-infra/s3_cache.py upload 'npm packages' test-infra/npm-shrinkwrap.canonical.json ./node_modules; fi
-  - if [ "$TWBS_TEST" = validate-html ]; then ./test-infra/s3_cache.py upload rubygems pseudo_Gemfile.lock $(rvm gemdir); fi
+  - if [ "$TWBS_TEST" = validate-html ]; then ./test-infra/s3_cache.py upload rubygems pseudo_Gemfile.lock $GEMDIR; fi
 env:
   global:
     - JEKYLL_VERSION: 1.5.0