rewriteutil: also consider pending obsoletes when updating hashes in messages Phabricator builds up the replacement commits and mapping in a single transaction, and then finalizes everything once the commits have been rewritten. That's too late when trying to update the messages for those commits. I'm a little concerned that this isn't a generic enough interface, since it doesn't mimic the list of list return of `obsutil.successorssets()`. But this is the type of mapping that phabricator maintains, and I don't think the methods that would be interested in calling this need to worry about split and divergence. We can fix that later if the need arises. Differential Revision: https://phab.mercurial-scm.org/D8949