rebase: show more useful status information while rebasing
Show status messages while rebasing, similar to what graft do:
rebasing 12:
2647734878ef "fork" (tip)
This gives more context for the user when resolving conflicts.
tests: make 'saved backup' globbing less narrow in rebase tests
Globbing the hash made it harder to maintain tests with run-tests -i when it
was so far by the generated test output.
The hashes are stable and we just need to add a (glob).