Update upstream

Spigot-Server-Patches/Fix-Double-World-Add-issues.patch

@@ -8,7 +8,7 @@ Vanilla will double add Spider Jockeys to the world, so ignore already added.
 Also add debug if something else tries to, and abort before world gets bad state
 
 diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
-index cee77e7a3..f5366ebf0 100644
+index 12bd558a7..8747d9a45 100644
 --- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 +++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 @@ -0,0 +0,0 @@ public class ChunkRegionLoader implements IChunkLoader, IAsyncChunkSaver {
@@ -21,7 +21,7 @@ index cee77e7a3..f5366ebf0 100644
              Iterator iterator = entity.bF().iterator();
  
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index 91cfed1e5..5672689cf 100644
+index 565b1d7e5..3cacf2c6d 100644
 --- a/src/main/java/net/minecraft/server/World.java
 +++ b/src/main/java/net/minecraft/server/World.java
 @@ -0,0 +0,0 @@ public abstract class World implements IBlockAccess {
@@ -29,7 +29,7 @@ index 91cfed1e5..5672689cf 100644
          org.spigotmc.AsyncCatcher.catchOp( "entity add"); // Spigot
          if (entity == null) return false;
 +        if (entity.valid) { MinecraftServer.LOGGER.error("Attempted Double World add on " + entity, new Throwable()); return true; } // Paper
-         // CraftBukkit end
-         int i = MathHelper.floor(entity.locX / 16.0D);
-         int j = MathHelper.floor(entity.locZ / 16.0D);
+ 
+         org.bukkit.event.Cancellable event = null;
+         if (entity instanceof EntityLiving && !(entity instanceof EntityPlayer)) {
 --