Catapults sometimes refuse to cancel unpacking

[causative]

Have noticed in a few games. If there's something in range of your catapult that it has decided to attack, and it starts to unpack but you tell it to cancel unpacking, sometimes your order will only reset its unpack progress bar to 0, and it will continue unpacking - it will refuse to go to a packed state unless you first allow it to finish unpacking.

As I recall, this always happens when you ungarrison or create the catapult within range of an enemy.