mxcl/homebrew — pull request #9559 by mtoledo (2012-01-12 15:25:21+00:00)
Title: Replacing "/usr/bin/ruby" with "/usr/bin/env ruby"

Some users like myself have their default ruby upgraded to a 1.9 version, which is currently incompatible with homebrew.

I think it shouldn't have any negative impacts on current users to load the environment ruby instead of the hardcoded /usr/bin/ruby, but it makes it easier for those whose ruby on the hardcoded path is incompatible.