Bukkit/CraftBukkit — comment on commit 27045d326f62bb2947d46b5aa81ea7d39f26a629
File: src/main/java/org/bukkit/craftbukkit/block/CraftChest.java line 25
By Acrobot:

This doesn't seem to work for me. If I do chest.getInventory() on a double chest, it always return a 27-slot CraftInventory, no matter how I place it.
Are you sure that "z" should be hashCode, not getLocation().getBlockZ()?