Affects Version/s: Minecraft 17w13a
Fix Version/s: Minecraft 17w13b
Minecraft PC / Java 1.8 64bit
Since parrots seem to spawn restricted by hostile mob cap, while they contribute to passive mob cap, this will cause in any world that loads within player range chunks with a jungle biome to crash.
In normal worlds it make take some time, but in general is inevitable, since parrots won't spawn.
I understand the care about existing users which are for the most part not conditioned to passive mob farming using natural spawning, but changing their spawning to follow fully passive mobs would be the easiest, obvious and adequate solution, however the method with ocelots (a.k.a. ozelot) by putting them in the hostile category that spawn in light, on grass and doesn't attack a player, and despawn randomly, would be another solution. Another solution would be to add them to the ambient category (add some company to bats) and make them despawn. Last solution would allow regular hostile mob density in jungle biomes, which is already slightly reduced by presence of ocelots.
Create world with jungle biome, works best with superflat worlds for many reasons, and AFK and notice entity count.