Copy and paste of two functions from Ubuntu 13.04's version of /usr/share/zsh/functions/Completion/Unix/_git that were referenced in 46f0d8d. Fixes #1952.
Merge pull request #1961 from brenttheisen/issue_1952_pr

Copy and paste of two functions from Ubuntu 13.04's version of /usr/s… …hare/zsh/functions/Completion/Unix/_git that were referenced in 46f0d8d.