Until you have merge conflict. If someone could explain to me which file contains the conflict markers so I can fix them I'd be really happy. Its not the .gitmodules file.
1. Create a new repo.
2. Get the branched submodule.
3. Check that in as head: Note, now HEAD will NOT compile - I've committed broken code.
4. Go back to the original repo.
5. Get HEAD: this pulls the hash I need.
6. Do the merge. The submodule doesn merge, because it has the right hash.
Surely there must be some way to just modify the hash. But I don't know where to change it. I found it in several locations, but I don't know how it works, and hacking my VCS isnt my idea of good sense.