Comment 15 for bug 1791989

I used query like: http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22'%5BFail%5D%20Couldn'%5C%5C''t%20ping%20server'%5C%22 to find such issues in the gates.
What I can say is that this issue happens only on:
- master branch - around 85% of cases
- stable/pike - around 15% of cases

There is no any issue like that on stable/ocata, stable/queens or stable/rocky branch. I was suspecting packages like libvirt, qemu or openvswitch but all of them are in completely different versions on stable/pike jobs and are failing also so it's not that IMO.

I'm really puzzled and I have no idea what could cause such issue.