Homebrew/homebrew — pull request #26582 by sh1mmer (2014-02-10 20:32:05+00:00)
Title: Try ssh when cloning taps before falling back to HTTPS

If you have Github 2factor on then HTTPS isn't very easy to use so I added a modification to tap install which tries SSH cloning first and then falls back to HTTPS. This makes a huge difference when cloning non-public repos.