Log Message:
py-hg-evolve: update to 9.3.1, needed with mercurial 5

joerg did not raise a clear objection when I asked, just alerted me
that there will be a mercurial and hg-evolve update `real soon now'.
Since it hasn't happened in the two weeks since I prepared this
patch, I'm reading the lack of objection as approval, with the
understanding that this update may be overwritten soon.