I was checking errors on the machines and found on glance.o.o:
http://mirror.centos.org/centos/7/cloud/x86_64/openstack-pike/repodata/repomd.xml:
[Errno 14] HTTP Error 404 - Not Found
Evgheny suggested that, since the new openstack release is incompatible with oVirt, we could publish a dump of the repo he happened to have under his sleeve.
This way the regular updates are not generating errors and we would be able to redeploy in cas of problem.