Trapdoors don't update blocks when opened

The bug

The lever or button installed on the trapdoor does not drop out if the trapdoor has opened.

To reproduce

• Place a trapdoor.

• Place lever or button on this trapdoor.

• Open this trapdoor. (It does not matter how, by a redstone or a hand)

• Notice that the lever / button is left hanging in the air. It breaks if you update the block next to it.