Headless pistons do not react to block updates

Headless pistons do not react to block updates and remain headless regardless of any updates.
Steps to reproduce: Get a headless piston, and place a redstone block next to it. Remove the redstone block.
What happens: Nothing
What should happen: The piston regains its head and retracts it. There should now be a normal sticky piston or normal piston in the place of the headless piston.