Iron trapdoors don't close when moved to an unpowered position my pistons.

1.Place the iron trapdoor next to a redstone power source.
2.Move it by piston to an unpowered position.
3.Block-update the trapdoor, and notice how it is still not closing.

The cause of this problem is, I think, the fact that iron trapdoors share the same code w/ their wooden variants.