Steps to reproduce:
Summon a Killer Rabbit: /summon Rabbit ~ ~ ~ {CustomName:Test,RabbitType:99}
Then, change its entitydata to another type of rabbit: /entitydata @e[name=Test,type=Rabbit] {RabbitType:0}
You will get a brown rabbit that attacks you!
Working as intended, see Searge's comment on MC-66293.