Game crashes when a fireball is shot

After hearing that the mob inter-aggro AI had finally been updated I tested pigmen to see if they again would attack other mobs that hit them.

It worked for the skeletons, however when struck by ghast/blaze fireballs they did not respond. Shortly after the game crashed. This happens almost every time I try to test this scenario though sometimes not right away. With ghasts it sometimes took about 10 seconds to finally crash but it did multiple times with both mobs

The crash log said that it was caused by a null pointer for a fireball. My guess is the pigmen are aggroing on the fireballs rather than the ghast/blaze that shot them? Then the game crashes when the fireball disappears.

To replicate:

with spawn eggs create a ghast/blaze. Summon a group of zombie pigmen. Set yourself to survival and stand behind the pigmen so the incoming projectiles hit them. The pigmen do not make an angry sound or aggro on the mob that shot even if they are within reach. from 1-10 seconds later the game will crash. I was on mavericks version of the mac version of minecraft if that makes a difference.

Description: Ticking entity

java.lang.NullPointerException: Ticking entity
	at aaa.a(SourceFile:44)
	at zu.m(SourceFile:117)
	at ahn.a(SourceFile:1467)
	at lp.a(SourceFile:719)
	at ahn.g(SourceFile:1445)
	at ahn.k(SourceFile:1335)
	at lp.k(SourceFile:552)
	at net.minecraft.server.MinecraftServer.D(SourceFile:625)
	at net.minecraft.server.MinecraftServer.C(SourceFile:553)
	at bxz.C(SourceFile:154)
	at net.minecraft.server.MinecraftServer.run(SourceFile:457)
	at java.lang.Thread.run(Thread.java:745)