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, 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.

This always happens when you ungarrison or create the catapult within range of an enemy. It also always happens if the catapult is ever idle within range of an enemy. The only workarounds are to use passive stance, or to wait for it to finish unpacking and then tell it to pack again, and give it an order while it's packing.

The root cause seems to be that catapults will choose targets and unpack to attack them on their own.

Alternatively, if you could give catapults an order while they are unpacking, which would cause them to both cancel unpacking and follow the order, this would also solve the problem, as well as being more convenient to the player in other situations.

[elexis]

(not sure if refs ​Phab:D1458)

[temple]

Haven't looked yet, but we tried fixing some issues with packing units in r21630 and later commits.

[elexis]

See also #4015 about cancel unpacking when receiving a move order.

[elexis]

Closing as dupe of #5328 (as that contains some more details)