It is possible that instance faults have the same created_at values so
ordering on that field alone is not deterministic. Add an additional
order by clause to order descending on id as well.
I am not sure if the order by exists to make tests pass; however,
without the additional "id" the tests do occasionally fail. See
http://logs.openstack.org/15078/18/check/gate-nova-python26/10709/console.html
for an example failure. If order does not actually matter we may want to
make the test smarter instead.
Part of blueprint grizzly-testtools
Change-Id: I1c7a07669846c832270631c1734dae509dba7586
fa5e490e46