1 of 2 pistons remained active after all redstone wire and lamps and pistons and all other blocks around it were destroyed. I replicated this bug several times.

What I expected to happen was...:
Once the restone wire above the pistons lost power, I expected both pistons to retract

What actually happened was...:
After cutting power to the redston wire, 1 of the 2 pistons remained powered

Steps to Reproduce:
1. In the "Before" image, everything works just fine
2. In the "After" image, the piston remains active
3. In the "Bug" image, all blocks around the active piston have been destroyed. You can also see in the background that I replicated the bug with both types of piston.

Now, this was in creative mode, but I feel it is worth mentioning that when I switched over to survival mode I was able to again replicate the bug with one exception. Upon destroying an adjacent block, (after destroying all redston) the piston DID retract.