considering that they have actual test code which also takes quite a while to run, I would assume that there are systems misbehaving in many different ways, all

considering that they have actual test code which also takes quite a while to run, I would assume that there are systems misbehaving in many different ways, all of which might cause this feature to break, so all of them needs to be tested against. The check you're talking about is one of the many checks it does, but there was further breakage which all needs to be checked against.