It should be noted that this also happens when moving a triggered observer with a piston, which is causing issues in flying machines.
Ways to reproduce:
This issue will heavily affect flying machines as the pulse appears longer than it actually is because of the missing update and the piston moves back the blocks in front instead of leaving them behind (as it would if it wouldn't move the observer).
([Mod] Neko Aww.. I made a duplicate To be fair, you created this issue while I was typing it as well :-P)