Fix pickup of dropped items when the player only takes a part of them

builtin/item_entity.lua

@@ -111,6 +111,7 @@ minetest.register_entity("__builtin:item", {
 		if self.itemstring ~= '' then
 			local left = hitter:get_inventory():add_item("main", self.itemstring)
 			if not left:is_empty() then
+				self.itemstring = left:to_string()
 				return
 			end
 		end