git: add alias that allows cd to the git-root

[cgundogan]

This is an alias that I use quite often to change quickly to the top-level directory of a git repo. I thought it might be a good idea to push this upstream, so that others can also benefit from it.

[Eriner]

I ask to have g.. be considered over grt, as it is more intuitive.

[cgundogan]

@Eriner I adjusted the grt alias to be g.. and amended the change immediately. You are right that it is more intuitive this way. Thanks for the feedback.

[Eriner]

No problem; sorry for not providing attribution correctly in my original PR, I didn't find it when searching. Great alias :+1:

[paulmelnikow]

Old thread, but thought I would share the version I use. I went with gcd for the alias.

# Inspired by http://jeetworks.org/node/52

cdup=$(git rev-parse --show-cdup)
# git rev-parse returns non-zero when not in a git repository
if [ $? -eq 0 ]; then
    # and an empty string when you're already at the root
    target=${cdup}${1}
    if [ -n "$target" ]; then
        cd $target
    fi
fi

It supports the usage above, and also lets you gcd modules/prompt/functions.

I've got a completion for it too, which is super handy, but it seems to be broken at the moment.