This patch fixes the changeset-centric version in a pretty
straight-forward way. It fixes it to automatically resolve the
conflict, which is better than resulting in a modify/delete conflict
as it was before b4057d001760 (merge: when rename was made on both
sides, use ancestor as merge base, 2020-01-22).
I'll leave it for later to test and explicitly handle cases where
files have been renamed to the same target on different sides of the