Don't need to update flavor if only access projects changed

[Liusheng]

Currently, in the objects layer, it will always call flavor_update() even only the flavor access updated.

related code:

    def save(self, context=None):
        updates = self.obj_get_changes()
        projects = updates.pop('projects', None)

        # access projects
        if projects is not None:
            deleted_projects = set(self._orig_projects) - set(projects)
            added_projects = set(projects) - set(self._orig_projects)
        else:
            added_projects = deleted_projects = None

        if added_projects or deleted_projects:
            self.save_projects(context, added_projects, deleted_projects)

        self.dbapi.flavor_update(context, self.uuid, updates)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/505004

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/505004
Committed: https://git.openstack.org/cgit/openstack/mogan/commit/?id=f10c8e1c2ed9edbd3f97ac870ccd0721211c0ae9
Submitter: Jenkins
Branch: master

commit f10c8e1c2ed9edbd3f97ac870ccd0721211c0ae9
Author: liusheng <email address hidden>
Date: Tue Sep 19 11:28:48 2017 +0800

    Don't need to update flavor if only access projects changed

    Closes-Bug: #1718092
    Change-Id: I043ecb9087eb3e8425432c6e325b7f87eaf96028