[MC-91764] Server crash on 15w44b ticking entity

The server kick out players randomly and close with the message ticking entity in the crash log, I join the crash report I get each time, we don't do anything specific while it happens but it didn't happen in 15w44a for sure and we played fine with it for 2 days.

Description: Ticking entity

java.lang.NullPointerException: Ticking entity
	at ry.a(SourceFile:445)
	at rx.a(SourceFile:833)
	at zf.a(SourceFile:634)
	at rx.a(SourceFile:766)
	at yw.a(SourceFile:61)
	at zf.a(SourceFile:235)
	at yx.a(SourceFile:148)
	at we.B(SourceFile:167)
	at to.e(SourceFile:121)
	at th.a(SourceFile:129)
	at ry.cd(SourceFile:620)
	at rx.n(SourceFile:1680)
	at ry.n(SourceFile:473)
	at we.n(SourceFile:120)
	at rx.m(SourceFile:1542)
	at ry.m(SourceFile:265)
	at aho.a(SourceFile:1481)
	at lq.a(SourceFile:719)
	at aho.g(SourceFile:1459)
	at aho.k(SourceFile:1349)
	at lq.k(SourceFile:552)
	at net.minecraft.server.MinecraftServer.D(SourceFile:618)
	at lb.D(SourceFile:314)
	at net.minecraft.server.MinecraftServer.C(SourceFile:546)
	at net.minecraft.server.MinecraftServer.run(SourceFile:450)
	at java.lang.Thread.run(Unknown Source)