def changeset_modified(self, repos, changeset, old_changeset):
        if self._is_duplicate(changeset):
            return
        tickets = self._parse_message(changeset.message)
        old_tickets = {}
        if old_changeset is not None:
            old_tickets = self._parse_message(old_changeset.message)
        tickets = dict(each for each in tickets.iteritems()
                       if old_tickets not in each[0])
        comment = self.make_ticket_comment(repos, changeset)
        self._update_tickets(tickets, changeset, comment, datetime_now(utc))
dataset/ETHPy150Open edgewall/trac/tracopt/ticket/commit_updater.py/CommitTicketUpdater.changeset_modified/swapped operands of `not in`