Updated openstack/openstack
Project: openstack/nova  b6122d52d5de4dc7cb755d4f081a14a4635d4a56
null
Fixed check in image cache unit test

Before the fix assert checked nothing bacause .sort() sorts
provided list and has no return. Comparison of two None objects
is always true.

Change-Id: I3d453a29b5913cd24ce8d9e4a2324c7ad8d138b7