phabricator: prevent posting obsolete commits I don't see why this would be useful in the first place. But I had a coworker submit a single commit that was not a branch head, and the result was to orphan its child and keep the original commit visible. He then did up arrow + Enter, and it happily created a new review (since the URL isn't amended into the original commit specified on the command line) and a new successor, resulting in a local divergence. I'd like to fix the issue with creating orphans, but this is simple enough to prevent on its own. Differential Revision: https://phab.mercurial-scm.org/D8437