I was in this position just recently where git suddenly stopped working, due to needing a complete update of xcode tools. Annoying blocker but OK, let's get it done.

But trying to download the xcode tools put me into a loop which wasn't completing for some reason. After several attempts waiting for it to download and install I gave up and created an alias 'git' which points to my brew install of git (in usr/local/bin I think).

This will bite me somehow very soon, I'm sure.