Siege units automatically pack after unpacking if they are in formation

[Langbart]

When a siege unit is in a formation, with one or more military units e.g.soldiers or other siege units and gets the order to 'unpack', it does so but immediately re-packs itself.

Also when I double click on 'unpack' I get these errors. They only occur if the siege units is in a formation, without formation a double click on 'unpack' will not produce errors.

ERROR: JavaScript error: simulation/components/UnitAI.js line 4206 order is undefined
UnitAI.prototype.GetOrderData@simulation/components/UnitAI.js:4206:7 
UnitAI.prototype.PushOrderFront@simulation/components/UnitAI.js:4051:74 
UnitAI.prototype.ReplaceOrder@simulation/components/UnitAI.js:4178:8 
UnitAI.prototype.AddOrder@simulation/components/UnitAI.js:5408:8 
UnitAI.prototype.CancelUnpack@simulation/components/UnitAI.js:5999:8 
cancel-pack@simulation/helpers/Commands.js:690:15 
ProcessCommand@simulation/helpers/Commands.js:53:23
ERROR: Failed to call ProcessCommand() global script function

In the GIF I tried first the 'unpack' in formation, then 'unpack' without formation and finally a double click in formation on 'unpack'. Tested with 0ad-0.0.24rc1-24875-alpha-osx64.dmg and SVN version 24892.
This behaviour can not be reproduced in the A23b bundle.
The pack/ unpack bug can first be noticed with [24467].
The double click error can first be noticed with [24869].

[Freagarach]

Probably due to the offsets, which tell the siege to move and hence to unpack.

[wraitii]

In 24895:

Fix issues with formation + packing.

• rP24869 contained a small mistake: this.order wasn't cleared when clearing the orderqueue, which led to a broken codepath in PushOrderFront.
• Since rP24467, formation orders their members to reform in IDLE. This will automatically pack any unpacked siege.

Reported by: langbart

Tested by: langbart

Fixes #6018

Differential Revision: ​https://code.wildfiregames.com/D3561

[Langbart]

adding D3561