Record the sqlalchemy object states in the middle of session,
        prepare the events for the final pub in session_commit.

def session_update(self, session, *_):
        """Record the sqlalchemy object states in the middle of session,
        prepare the events for the final pub in session_commit.
        """
        self._session_init(session)
        session.pending_write |= set(session.new)
        session.pending_update |= set(session.dirty)
        session.pending_delete |= set(session.deleted)
        self.logger.debug("%s - session_update" % session.meepo_unique_id)