branch: add tests which shows branch can be closed from a non-branchhead cset This patch shows that we can close a branch even from a cset which is not a branch head. It was supposed to abort this operation. Next patch will be fixing the issue. Differential Revision: https://phab.mercurial-scm.org/D6281

phabricator: read more metadata from local:commits local:commits metadata can contain branch info, and 'rev' has been superseded by 'commit', see: https://github.com/phacility/arcanist/blob/83661809e532c3fe444a8bf7c7d6936e6377691b/src/repository/api/ArcanistMercurialAPI.php#L281 Differential Revision: https://phab.mercurial-scm.org/D6300