Not sure if bug or fix, but I don't like it, it will break many redstone builds or make them take a much longer time. Sticky pistons don't leave the block out if they receive a 1-tick pulse.
I expected the sticky piston to leave the block there.
The piston retracted and pulled the block back.
Steps to Reproduce:
1. build mono-stable circuit with piston attached to output
2. power the mono-stable circuit with a button or lever
3. observe that the sticky piston keeps the block when it previously didn't.
Related issues
duplicates
Comments

Duplicate of MC-6099.