If you've ever find that Bundler insists on putting gems in vendor/cache and you can't make it stop, check the .bundle/config file and you will find a directive that was written there as a result of a bundle install –path vendor/bundle command you did previously. Once you execute this command, bundler will write gems to this directory forever more unless you delete the directive. This can be maddening as .bundle/config isn't a file that many of us look at.