title: moving commits from unrelated repository in git, git-p4
body: <p>I've been learning git and git-p4 and have ended up in a situation where I can't 'git-p4 submit' anymore; patches don't cleanly apply.</p>
  
  <p>I can always re-clone the p4 depot and copy my new changes over the top and 'git-p4 submit', but I'd like to maintain my commit history in the new git repository.  Given that the old and new repositories start from an identical state, is there a way of moving commits from the old to the new, even thought the new wasn't 'git clone'd from the old?</p>