rebase: on abort delete rebase state file no matter what When a user's repository is in an unfinished rebase state and they choose to abort, at a minimum, the repo should be out of that state. We've found situations where the user could not leave the state unless manually deleting the rebasestate file. This fix ensures that no matter what exception may be raised during the abort, the rebase state file will be deleted, the user will be out of the rebase state and they can get their repository into a workable condition.