commit: add a check if it is trying to close an already closed branch head
It would check if the revision we are going to close is already a
closed branch head and print the error message accordingly.
Differential Revision: https://phab.mercurial-scm.org/D6491
Martin von Zweigbergk <martinvonz@google.com> [Mon, 17 Jun 2019 10:19:41 -0700] rev 42491
strip: use bailifchanged() instead of reimplementing it
This also means that we get the standard error messages (see changed
test cases).
Differential Revision: https://phab.mercurial-scm.org/D6535