Which :class:`.Changelist` is this revision in

def changelist(self):
        """Which :class:`.Changelist` is this revision in"""
        if self._changelist:
            return self._changelist

        if self._p4dict['change'] == 'default':
            return Default(connection=self._connection)
        else:
            return Changelist(str(self._p4dict['change']), self._connection)