def _migrate_abstract_judgments(self, old_abstract):
        if not hasattr(old_abstract, '_trackJudgementsHistorical'):
            self.importer.print_warning(
                cformat('%{blue!}Abstract {} {yellow}had no judgment history!%{reset}').format(old_abstract._id),
                event_id=self.event.id)
            return

        history = old_abstract._trackJudgementsHistorical
        if not hasattr(history, 'iteritems'):
            self.importer.print_warning('Abstract {} had corrupt judgment history ({}).'.format(old_abstract._id,
                                                                                                history),
                                        event_id=self.event.id)
            return
        for track_id, judgments in history.iteritems():
            seen_judges = set()
            for old_judgment in judgments:
                judge = old_judgment._responsible.user if old_judgment._responsible else None
                if not judge:
                    self.importer.print_warning(
                        cformat('%{blue!}Abstract {} {yellow}had an empty judge ({})!%{reset}').format(
                            old_abstract._id, old_judgment), event_id=self.event.id)
                    continue
                elif judge in seen_judges:
                    self.importer.print_warning(
                        cformat("%{blue!}Abstract {}: {yellow}judge '{}' seen more than once ({})!%{reset}")
                        .format(old_abstract._id, judge, old_judgment), event_id=self.event.id)
                    continue

                new_judgment = Judgment(creation_dt=as_utc(old_judgment._date),
                                        track_id=old_judgment._track.id, judge=judge)

                seen_judges.add(judge)
                if old_judgment.__class__.__name__ == 'AbstractAcceptance' and old_judgment._contribType:
                    contrib_type = old_judgment._contribType
                    try:
                        new_judgment.accepted_type = self.legacy_contribution_type_map[contrib_type]
                    except KeyError:
                        self.importer.print_warning(
                            cformat("%{blue!}Abstract {}: {yellow}contribution type '{}' unknown!%{reset}")
                            .format(old_abstract._id, getattr(contrib_type, '_name', contrib_type)),
                            event_id=self.event.id)
                yield new_judgment