Comment 3 for bug 1658033

So while the original submitter was able to work around this, it is still true that if machines are added as controllers and then fail to provision, they get stuck because we refuse to let you remove controller machines, but they aren't up for you to take them out of the HA group.
Probably peer-grouper needs a way to flag these as no-longer-important so that we can remove them. (see bug #1648799 or bug #1449633)