Remove undocumented git-info configuration
Remove undocumented git-info configuration

`prompt.showinfo` for enabling or disabling it globally or per
repository. It can be globally disabled by not loading the `git-info`
module at all, and prompts currently will not break (and in the future
should still not break) if the module is not loaded.

This removes one git call that is used to check for the
`prompt.showinfo` configuration value.

Eriner/zim,joshuarubin/dotfiles,joshuarubin/dotfiles,joshuarubin/dotfiles,joshuarubin/dotfiles