Clean up the cached dir if there is no cache

Author: ignisf

.travis.yml

@@ -34,6 +34,7 @@ before_install:
   - if [ "$TRAVIS_OS_NAME" == "linux" ]; then gem update bundler; fi
   - if [ "$TRAVIS_OS_NAME" == "osx" ]; then sudo gem install bundler; fi
 script:
+  - if ! [ "$(ls -A vendor/v8/.git)" ] ; then rm -rf vendor/v8; fi
   - MAKEFLAGS+=-j8 bundle exec rake spec binary --trace
 deploy:
   provider: releases