commit: check branch change on to-be-committed changeset...
commit: check branch change on to-be-committed changeset
This makes a difference when a branch name is passed via the `extra` argument,
which will be used as the branch name for the created changeset. The empty
commit check should use that branch name instead of whatever was set on the
working directory.
Besides fixing the bug for which a test case was extended, it enables to remove
a workaround in the rebase extension, which will be done in a follow-up patch
(D8725).
Differential Revision:
https://phab.mercurial-scm.org/D8724
