Piston Glitch
I noticed that when the redstone signal sent to a piston turns off, the piston moves to the side.
Environment
Java 1.8.0_25 64bit; CPU Intel Celeron CPU G1620 2.70GHz; Intel HD Graphics; Windows 10 Pro 64bit, 8GB RAM
Created Issue:
Piston Glitch
I noticed that when the redstone signal sent to a piston turns off, the piston moves to the side.
Environment
Java 1.8.0_25 64bit; CPU Intel Celeron CPU G1620 2.70GHz; Intel HD Graphics; Windows 10 Pro 64bit, 8GB RAM

I cannot confirm, I did a powered piston pushing a slime block pushing obsidian and it didn't do anything either when i flipped the switch powering the piston on or off.
Please force a crash by holding F3+C for 10 seconds and attach the resulting crash report here.