Git Followup
I got an amazing array of answers to my question, and I thought I would share with you all, the answer I was looking for, care of Nathan Corvino, among others.
The initial error, about updating the current branch of a working copy is denied because it will make the index and and work tree inconsistent, and will require a git reset --hard to fix it, is there to prevent you from forcing changes over someone else’s local work.