Dolphins aren't neutral mobs anymore

If my memory is correct, dolphins used to retaliate against other things, but now they just swim around, not a care in the world.
How to reproduce:
1. Spawn or find a dolphin
2. Be in survival mode
3. Punch the dolphin
What is expected:
The dolphin and its pod attack you.
What happens:
The dolphin just swims around, not caring at all.