The update by rebase code reuses the merge code but shortcircuits and
pushes back up to the head. However, it doesn't set the correct pushing
environment - and just uses the same environment as the base repo. This
leads to the push update failing and thence the PR becomes out-of-sync
with the head.
This PR fixes this and adjusts the trace logging elsewhere to help make
this clearer.
Fix #18802
Signed-off-by: Andrew Thornton <art27@cantab.net>
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
4199d28053