Previous default output remains when test cases are run individually. ok tracey

While merging a commit multiple times during a histedit operation could potentially make sense in some corner case, a commit appearing more than once in the script is more likely to happen accidentally. If desired, the same effect can still be achieved by running multiple histedit operations, or by using 'got cherrypick' while the histedit operation is paused for arbitrary editing.

Commit IDs on histedit's temporary branch can change arbitrarily because the user may create new commits on this branch while editing past commits. So there is no point in trying to verify these IDs like we do during rebase. Add a test case which demonstrates the problem.