From c77ae6f712e3d8402a0aafe3e543cae5b24754d9 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 e74b53c48..01041ede9 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1485,7 +1485,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
         }
 
         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.ae != i || entity.af != j || entity.ag != k) {
@@ -1493,7 +1493,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
                 this.getChunkAt(entity.ae, entity.ag).a(entity, entity.af);
             }
 
-            if (!entity.bN() && !this.isChunkLoaded(i, k, true)) {
+            if (false && !entity.bN() && !this.isChunkLoaded(i, k, true)) { // Paper - Always send entities into a new chunk, never lose them
                 entity.inChunk = false;
             } else {
                 this.getChunkAt(i, k).a(entity);
-- 
2.18.0