Rabbits sometimes show up as having the name "entity.KillerBunny.name"

The affected rabbits I'm dealing with were spawned in a world created in 14w29b using no commands. They had no nametag above them until I upgraded to 14w30c. There's also two other rabbits, around this black one outside of this screenshot, that also have this nametag above them. Also all of the rabbits are tamed.