There are quite a few zsh init scripts available out there which implement git integration. Unfortunately, they also slow down the shell workflow. I have found myself continuously frustrated by the fact, how much they make switching between directories slower. In the end, I have tried implementing something on my own and result is reasonably faster than `oh-my-zsh` or other solutions.
You can get the code from:
git clone git://github.com/gnufied/dot_files.git
Be warned that, it may or may not work with old version of zsh or git.