No changes for m2m field when edit through admin

[sneawo]

When i edit an object with m2m field through admin there is no m2m_changed signal and m2m changes are not synced.

Maybe it's better to add M2M_CHANGE action for each ADDITION and CHANGE?

            if del_time is None or last_time > del_time:
                ACTIONS[log.action](log.content_type, log.object_id, log)
                if log.action in [ADDITION, CHANGE]:
                    ACTIONS[M2M_CHANGE](log.content_type, log.object_id, log)