Git tab completion not working in zsh on mac

No matter what I try and do I can't seem to make git tab/auto completion work in my zsh shell. I've downloaded the bash-completion script and the zsh-completion one and followed the instructions, but I can't make it work.

I've reinstalled oh-my-zsh but that didn't seem to help or make any difference.

Can anyone who's got it working describe to me their setup so I can try an emulate it to get it working for me?

To be specific, what I've done so far is:

• Switched to using zsh as my default shell
• Installed oh-my-zsh
• Downloaded https://github.com/git/git/blob/master/contrib/completion/git-completion.bash and saved it in ~/.completion/git/git-completion.sh
• Downloaded https://github.com/git/git/blob/master/contrib/completion/git-completion.zsh and saved that in ~/.zsh/_git
• Added zstyle ':completion:*:*:git:*' script ~/.completion/git/git-completion.sh

No luck.

The answer was that I had alias git=hub in my .zshrc file. See https://github.com/github/hub for info on hub (it's awesome).

Here's a link to info about the problem I was having with hub and git completion: https://github.com/github/hub/issues/586#issuecomment-47727226