this no longer happens and can be resolved.

Thank you.
I'll keep this open until next week and if I do not see it repeat I will close.

Thank you for the help Milan!

There has already been experience in OST with a similar problem, resolved by using a different check. So I posted a patch changing the check in preview_snapshot_with_memory: https://gerrit.ovirt.org/93216

@Milan Zamazal thanks for looking in to this.
looking again at the last failure it's not in ovirt-engine but in ovirt-ansible-disaster-recovery and in 4.2
usually I would say that because its not in a specific project its probably the test but because its a completely random failure there is a chance that its been merged and not failed CQ.
So lets wait to see if its an actual regression and not skip at this time.

I looked into the problem and I'm not sure whether the check in the test is based on wrong assumptions or whether there is a bug in Engine / REST API. I've sent a question to oVirt devel mailing list. Depending on the answer either the test in OST should be fixed or oVirt should be fixed. If the failure causes too much trouble in the meantime, you can disable make_snapshot_with_memory + preview_snapshot_with_memory + check_snapshot_with_memory tests in 004_basic_sanity.py.