Updated openstack/openstack
Project: openstack/nova  10fc67a8ec50ea1f9b39d8026f4914c52fe3a352

libvirt: convert volume usage test case to avoid DB usage

Convert LibvirtVolumeUsageTestCase so that it avoids creating an
instance in the database. This allows it to be switched over to
use NoDBTestCase, improving perf from 1.7s to 0.13s.

Partial-bug: #1369516
Change-Id: If2ab915388c2a1ba0565d4aa8bb66b98db535094