From 245331c039b6ab15566074240a09fb88a06a0f1a Mon Sep 17 00:00:00 2001
From: Alexander Weber <web.alexander@web.de>
Date: Fri, 16 Dec 2016 13:27:57 +0100
Subject: [PATCH] bugfix: do not change the template node group! the groups
 copy "by reference" and change them did affects the template node groups
 (leafdecay, falling_node) Now the groups table is copied by value so the
 template node definition is not touched anymore

---
 api.lua | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/api.lua b/api.lua
index 59a5552..31fb73b 100644
--- a/api.lua
+++ b/api.lua
@@ -34,16 +34,27 @@ function carpets.register(recipe, def)
 	local recipe_def = minetest.registered_nodes[recipe]
 
 	node.description = node.description or recipe_def.description .. " Carpet"
-	node.tiles       = node.tiles       or recipe_def.tiles
+	node.tiles = node.tiles or recipe_def.tiles
 
-	if node.tiles[6] then -- prefer "front" site for carpet
+	if node.tiles[6] then
+		-- prefer "front" site for carpet
 		node.tiles = {node.tiles[6]}
 	end
 
-	node.sounds = node.sounds or recipe_def.sounds
-	node.groups = node.groups or recipe_def.groups or {}
+	if not node.sounds then
+		--copy by reference because no change expected
+		node.sounds = recipe_def.sounds
+	end
 
-	node.groups.leafdecay = nil
+	if not node.groups then
+		node.groups = {}
+		-- copy by value because of some changes
+		for k, v in pairs(recipe_def.groups) do
+			node.groups[k] = v
+		end
+
+		node.groups.leafdecay = nil
+	end
 
 	if config:get_bool("FallingCarpet") and node.groups.falling_node == nil then
 		node.groups.falling_node = 1