Observers activating before 1 tick.

To reproduce the bug you need a piston, a sticky piston, two observers, two slime blocks, and a button. Place the piston sticking up. Take an observer and place it powering into the piston. Place two slime blocks on top. Take a sticky piston with the head facing towards the slime blocks then put the second observer powering into the sticky piston. Use button to activate first piston, then place button on second one when it breaks. Make sure you are at a position where you can see the observers flashing. 

The observer is supposed to flash after 1 second. Currently it is flashing after 1/2 second. The 1/2 second flashing effects red stone timing. The piston requires a full second to retract. The current timing is causing red stone mechanisms to break.