tests: add commit hashes to log commands in rebase tests Commit hashes are a useful way to ensure the content of commits made in the tests are not changing, even if we don't query every aspect of every commit. (And some properties, like extras, are rarely printed at all.) Many of the rebase log -G calls didn't show hashes; by adding hashes to places that weren't showing them we can help protect those tests from unwanted changes. Differential Revision: https://phab.mercurial-scm.org/D1650