Wall bugs just like with Glowstone

So there is this bug when you extend a piston out place a minecart below it and then enter said minecart the backside (relative to the extended side) will be able to see trough just like the glowstone bug in earlier version used to be, but just in one direction. It is fairly cheap and there very abuse able to get an advantage in mining against people on survival servers, see it as an legit x-ray.  A picture showing what it looks like is attached below.

 

Edit: Bug also works with stair and any half or not complete block.