Redownloading Minecraft (and server) fixes this.
I got into my 1.6.1 world in the 1.6.2 prerelease and was attacked by 3 baby zombies (not villager baby zombies)
Knowing these shouldn't spawn like this I switched to creative mode and gave myself a Spawn Zombie.
I spawned over 9 baby zombies from the spawn egg and 1 villager baby zombie.
This breaks the game's normal gameplay and should not push 1.6.2.
Ways to reproduce:
- Zombie spawn egg
- Only baby zombies spawn
- play survival and notice baby zombies
also zombie pigmen babys spawn