While testing the fix for MC-119971, I discovered a weird problem with pistons. It seems like if there's a sticky piston trying to pull at a chunk border, and the chunk on the other side of the border is unloaded, then the piston gets stuck in a permanently extended state.

This might be related to MC-89146, but in this case, the piston is getting constant updates from a pulsing redstone line right next to it on an obsidian rail.

Steps to reproduce:

• Go to MC-119971 and download the world file I provided there.
• Load that up in the latest snapshot.
• Teleport to around X=0,Z=0 and take note of the way that the pistons and slimeblock machine moves back and forth across a chunk border.
• Teleport to around X=150, get into the minecart, and AFK for a minute or two.
• Teleport back to the machine and observe that the sticky piston is stuck extended.