Bug observed in version .40.05, the world is also generated in .40.05.
In the save, the Trader about to Pit/Pond a caged minotaur is two tiles away from the cage, surrounded by military dwarves.

After the minotaur is released, people start fighting those who take up the Pit/Pond job, but when it is killed, the hostilities stop.
Sometimes the military will kill the minotaur before they attack the Trader, which might prevent the bug from making itself apparent.