[1.2] Colonist can block caravans from digging the room they are trapped in

[quandangv]

This loophole allow players to steal all the goods from any caravan while gaining ~80 goodwill with the faction. I uploaded a video of the exploit here: https://youtu.be/24nT1pZBN2A

• Players can trap the caravan members in a room with heaters by having a dining room near the caravan's gathering. When the members realize they are trapped, they will try to dig out of the room
• The members won't dig at places that are being or queued to be repaired by a colonist. If a colonist is queued to repair most of the walls of the room, the members will not dig at all. This allow players to cause heatstroke to the caravan members and animals. Players can then steal the caravan goods and rescue caravan members to get goodwill
• Caravan members should ignore what colonists do and keep digging in that situation.
• To reproduce this:
  
  
  
  • Wait or use dev mode to call a caravan
  • Have a dining room near the caravan gathering and block the doors when caravan members go to eat, or build walls enclosing the caravan
  • When the caravan try to dig out, prioritize a colonist to repair the walls (preferably someone bad at construction). Queue all the damaged parts of the walls for repair.
  • Caravan members will have no place to dig and just wanders around.
• The original save game file have been lost, but I think the problem is easily reproducible. Tell me if I'm wrong, I will reproduce the save game file.

[Pheanox]

Thank you as well for this very well documented bug report, I'll have the devs review it.