SPIGOT-887: Fix getOwner() on internal sheep inventories.

nms-patches/InventoryCrafting.patch

@@ -1,5 +1,5 @@
---- /home/matt/mc-dev-private//net/minecraft/server/InventoryCrafting.java	2015-02-26 22:40:22.763608137 +0000
-+++ src/main/java/net/minecraft/server/InventoryCrafting.java	2015-02-26 22:40:22.763608137 +0000
+--- ../work/decompile-c2c33c10/net/minecraft/server/InventoryCrafting.java	2015-05-21 16:56:31.913113856 +1000
++++ src/main/java/net/minecraft/server/InventoryCrafting.java	2015-05-21 16:56:31.913113856 +1000
 @@ -1,5 +1,13 @@
  package net.minecraft.server;
  
@@ -46,7 +46,7 @@
 +    }
 +
 +    public org.bukkit.inventory.InventoryHolder getOwner() {
-+        return owner.getBukkitEntity();
++        return (owner == null) ? null : owner.getBukkitEntity();
 +    }
 +
 +    public void setMaxStackSize(int size) {