bookmarks: test for exchanging long bookmark names (issue5165) As far as I can tell a test for a long bookmark name never actually got added when this was fixed. Let's document that a 300 byte bookmark is something we're supporting (this patch started out life over a year ago as a way for me to validate the problem, and I recently found it.) I think the nonzero exits from the push operations are only because no new changesets get exchanged. Please correct me if I'm wrong on that. :) Differential Revision: https://phab.mercurial-scm.org/D2727