Comment 3 for bug 1761775

The api_db sync was added to grenade back in mitaka, when order didn't really matter, so it was probably not done that way intentionally:

https://review.openstack.org/#/c/190399/

And when upgrading from ocata->pike (cells v2 was required starting in ocata), the old side of grenade in that scenario, ocata, would be installed with devstack, which syncs the API DB first before the cell (nova) DB.