Fixed bucket overwrite inhibiting its role

- Buckets couldn't be used to take default:water_source nor default:lava_source
   because the overwrite made in homdecor/exterior.lua replaced that way of
   working. This patch makes both well and sources work.

homedecor/exterior.lua

@@ -328,6 +328,7 @@ homedecor.register("well", {
 })
 
 if minetest.get_modpath("bucket") then
+	local original_bucket_on_use = minetest.registered_items["bucket:bucket_empty"].on_use
 	minetest.override_item("bucket:bucket_empty", {
 		on_use = function(itemstack, user, pointed_thing)
 			local wielditem = user:get_wielded_item()
@@ -342,8 +343,10 @@ if minetest.get_modpath("bucket") then
 				else
 					minetest.chat_send_player(user:get_player_name(), "No room in your inventory to add a filled bucket!")
 				end
+				return wielditem
+			else
+				return original_bucket_on_use(itemstack, user, pointed_thing)
 			end
-			return wielditem
 		end
 	})
 end