Playing a peaceful game, a footman asked to join my town, so I accepted and forgot about him. I really just wanted to see the shepherd in action. Later, once my trapper was third level, I converted the trapper into a shepherd and laid down the appropriate zone. As soon as a sheep spawned, the footman ran over and started attacking. However, the sheep was not harmed. The shepherd came over and took the sheep, but the footman kept fighting, all alone, and kept taking damage, apparently from himself. He killed himself before I could demote him 
The game briefly locked up, than spawned dozens of error messages. I would be happy to upload the save from immediately afterwards.
To reproduce:
- Convert Hearthling to a footman.
- Convert another Hearthling to a Trapper.
- Get Trapper to level 3.
- Promote Trapper to Shepherd.
- Place pasture zone.
- Watch footman run to attack new-spawned sheep.
- Witness in horror that all the footman’s attacks damage himself as sheep walks away.
I converted a second Hearthling to a footman, and he immediately ran over to the sheep, started attacking, and killed himself. I can upload the save if necessary.