Repo was born to resolve this kind of problem, but it might not be a "good" one. We (git/gerrit team at Google) are working on bring cross-repository atomic submit and other stuff to git/gerrit and our goal is to replace repo with git submodule.
Here're a very brief slides[1] and notes[2] about this topic at this year's Gerrit User Summit.
That's very interesting, as someone who occasionally contributes to the odd Android fork. I kind of feel like repo is this weird semi-black box which does things I don't expect, like reverting my topic branches back to the remote branch but leaving the name in place (it does this if your topic branch does not have a remote tracking branch, and you run repo sync). I feel that at a minimum repo should play nice with standard git workflows. I should probably just read the repo source but I can't imagine why this behavior would be a good idea, and I'm usually left feeling like I would rather just use git directly than repo most of the time.
Repo was born to resolve this kind of problem, but it might not be a "good" one. We (git/gerrit team at Google) are working on bring cross-repository atomic submit and other stuff to git/gerrit and our goal is to replace repo with git submodule.
Here're a very brief slides[1] and notes[2] about this topic at this year's Gerrit User Summit.
[1] https://docs.google.com/presentation/d/1qG1eAiDmyozZBiVE6R4A...
[2] https://docs.google.com/document/d/1a2eFhVr1HUiKOjhaRHn_89mf...