Homebrew/homebrew — pull request #31981 by mikemcquaid (2014-08-30 12:30:36+00:00)
Title: Use bundler for test gem dependencies.

I realise @jacknagel may not like this which is why it's a PR. I've been unable to run the tests locally for quite a while due to `gem` and `rbenv` fighting and this is the only way I've got them to build.

I'm open to adding a `HOMEBREW_NO_BUNDLER` or the opposite if that would make this more amenable.