Several fixes to support Mercurial 3.1.1

Created originally on Bitbucket by Alex Nistico

Was already merged in Bitbucket before import, marked as merged by the import user

Source changeset not longer availableat the time of import. Commit listwill look empty

Compatibility with Mercurial 2.8.1 has been maintained. More comments are interspersed in the changes and commit messages.