Comment 5 for bug 1712432

Though I have to admit that that error message is really deep into mistral and we should fail harder and sooner if the package isn't installed; problem is we wanted it to be optional so right now the only thing we have is a warning message in the pre-deployment validations [1], not sure if that is visible in the promotion job, we probably don't run validations there.

1. https://review.openstack.org/#/c/483345/