From that link: At Google, our philosophy is that “rollbacks are normal.” When an error is found or reasonably suspected in a new release, the releasing team rolls back first and investigates the problem second.

I like that -- reminds me of aviation, where a go-around is normal. If your approach to landing isn't stabilized, you're too high, too low, too fast, too slow, etc. don't try to save it. Go around and try again.