Pistons lose piston head when pushing the block which powers it

The bug

Pistons lose piston head when pushing the block which powers it.

How to reproduce

1. Place a piston facing horizontal or up
2. Place a solid block attached to the piston head
3. Place a button on top of the solid block, and push the button
   → The piston pushes the block and loses its piston head, and cannot be updated