The gate surely runs into libvirt bugs on a regular basis, but we don't
capture those logs in logstash, so we can't write elastic-recheck
queries against them.
For example, I believe the underlying cause of this issue is libvirt:
https://bugs.launchpad.net/tempest/+bug/1276778/comments/10
Change-Id: Ie2f03b19249967e78319a4016921f91ef0498540