From 02cbb5810774ec0d8eb43b6cd5796a3d43878fe1 Mon Sep 17 00:00:00 2001
From: "0gb.us" <0gb.us@0gb.us>
Date: Thu, 28 Mar 2013 01:24:48 -0700
Subject: [PATCH] Fix node replacement in not-quite-loaded chunks

When first entering an area, sometimes placing nodes replaces other nodes that are not buildable_to. This seems to be caused by the fact that nodes in unloaded map blocks are treated as ignore, a node that is buildable_to. This fixes that, by using get_node_or_nil() instead of the previously-used get_node(), then checking to see if the nodes were actually loaded before replacing.
---
 builtin/item.lua | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/builtin/item.lua b/builtin/item.lua
index 1349fdf6..8e2f75a1 100644
--- a/builtin/item.lua
+++ b/builtin/item.lua
@@ -129,11 +129,18 @@ function minetest.item_place_node(itemstack, placer, pointed_thing)
 	end
 
 	local under = pointed_thing.under
-	local oldnode_under = minetest.env:get_node(under)
+	local oldnode_under = minetest.env:get_node_or_nil(under)
+	local above = pointed_thing.above
+	local oldnode_above = minetest.env:get_node_or_nil(above)
+
+	if not oldnode_under or not oldnode_above then
+		minetest.log("info", placer:get_player_name() .. " tried to place"
+			.. " node in unloaded position " .. minetest.pos_to_string(above))
+		return itemstack
+	end
+
 	local olddef_under = ItemStack({name=oldnode_under.name}):get_definition()
 	olddef_under = olddef_under or minetest.nodedef_default
-	local above = pointed_thing.above
-	local oldnode_above = minetest.env:get_node(above)
 	local olddef_above = ItemStack({name=oldnode_above.name}):get_definition()
 	olddef_above = olddef_above or minetest.nodedef_default