Comment 12 for bug 1251920

I think gate is unstable since this commit.
https://github.com/openstack/nova/commit/755f6194e29c8e3daf6fd64a59dc2be4c81b1f0d

We are running tempest in our internal environment, tempest is stable until this commit. I'm yet to revert this patch and verify. If someone want to verify against gate (without merge), go for it.