I've just upgraded our vSZ cluster from from 5.1.0 to 5.1.2 and now having multiple realms in the realm field separated by a comma (as the description says you can do) in the Administration -> AAA no longer works.
Used to work fine in 5.1.0, in 5.1.2 you can't log on using either realm. I'm guessing when they adding the default role mapping they broke it.
Sadly I'm not even going to try and open a ticket after my last experience. I'll just leave it here in case someone else ever runs into it