Merge branch 'mz/rebase-tests'

* mz/rebase-tests: rebase topology tests: fix commit names on case-insensitive file systems tests: move test for rebase messages from t3400 to t3406 t3406: modernize style add tests for rebasing merged history add tests for rebasing root add tests for rebasing of empty commits add tests for rebasing with patch-equivalence present add simple tests of consistency across rebase types