Bug with pistons in redstone snapshot

What I expected to happen was that the piston would push the redstone block up, but only with power

What actually happened was the redstone block (meant to be pushed) powered the piston

Steps to Reproduce:
1. Place a piston facing up
2. Put a redstone block on-top of the piston
3. Power the piston
4. Stop powering the piston

Conditions:
-Creative
-Redstone ready superflat