topic: adjust head checking wrapping to not interfere with concurrent push In the previous form, the new topic head was detected as affected and the push was rejected. We introduce a of 'test-topic-push.t' using the new race checker as there have been many compatibility issue with this new checkers.

topic: also detect head checking using the concurrent part

test: avoid 'test-check-commit.t' complaining copied code We switch to git diff.

topic: small test cleanuo The section was repeated.