Updated openstack/openstack
Project: openstack/nova  73677a887d4102f7c19afa3fc7a8ad286c1d722d

DB: use assertIsNotNone for unit test

Commit 48de2895b9a550a0944b31212349275605a4061d added a
validation that should have used assertIsNotNone.

TrivialFix

Change-Id: Ib6b82d90bb163f7ee06c916e52d3dd40ff2ba34d