rails/rails — pull request #4684 by rossmeissl (2012-01-26 04:38:11+00:00)
Title: Use `:rubygems` shortcut as standard Gemfile's `source` instead of explicit URL

Theoretically this would future-proof Gemfiles against possible (albeit unlikely) change in the rubygems URL.

[Documentation](http://gembundler.com/gemfile.html)