Merge Edges of Shapes in Shape Tool

It would be great if, when creating shapes using the new Shape Tool, edges that were on top of each other would merge. For example, in a square room I draw a right triangle that follows two walls of the room and then cuts across with a diagonal line. Right now if you do that you end up with two wall segments on top of each other. Ideally this would not happen and the diagonal wall would simply merge into the existing walls.