Re: [PATCH] Bug: failed octopus merge does not create MERGE_HEAD

Hmm.

When it detects conflicts, and refuses to make a merge, the octopus backend says "should not be doing an octopus". As far as I can tell, MERGE_HEAD is useful only when resolving conflicts, and the octopus strongly discourages recording anything but the simplest conflict-free merges. That makes me think that not writing the file out would be the more correct thing to do.

One possibility I can think of is that we try to prevent user mistakes by checking the existence of MERGE_HEAD (i.e. "can't do this, you are still during a merge"), and not writing MERGE_HEAD in this case, but still potentially leaving the index unmerged, may allow some operations that we should prevent from being invoked to proceed. Is that the issue you are trying to address? Or is there something else? Why do you want to have MERGE_HEAD?