Are you using some oh-my-zsh github plugin by any chance?
https://github.com/robbyrussell/oh-my-zsh/wiki/Plugins#githu...
oh-my-zsh is, imho, way overengineered and bloated. Leads to all sorts of issues like the one you're encountering there.
I would recommend sticking to a plain zshrc file that you can read, edit and fully understand.
The one I wrote and am using day to day is available here, with documentation: https://github.com/jleclanche/dotfiles
Are you using some oh-my-zsh github plugin by any chance?