From 9db121d4d39ef91745ee6901e0353950ff6dae5e Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 21 Sep 2016 22:54:28 -0400
Subject: [PATCH] Chunk registration fixes

World checks and the Chunk Add logic are inconsistent on how Y > 256, < 0, is treated

Keep them consistent

diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 3d43f2937..b07229875 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1467,7 +1467,7 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
         }
 
         i = MathHelper.floor(entity.locX / 16.0D);
-        j = MathHelper.floor(entity.locY / 16.0D);
+        j = Math.min(15, Math.max(0, MathHelper.floor(entity.locY / 16.0D))); // Paper - stay consistent with chunk add/remove behavior
         int k = MathHelper.floor(entity.locZ / 16.0D);
 
         if (!entity.inChunk || entity.chunkX != i || entity.chunkY != j || entity.chunkZ != k) {
-- 
2.20.1