I thought this would happen, and at first it didn't, but now it has.
So, in my most recent fortress I'm in a desert, and I had my woodcutters chopping the wood in the caverns. Due to this, my cage traps captured many troglodytes, which I pitted and disposed of (by putting fortifications on the edge and the trading post on the other side so that their archers A) give me arrows and B) kill the troglodytes.) Well, I recently received a goblin siege. There would've been no casualties but I was dumb. The leader got captured in a cage trap and the rest hovered around him. I sent my archers after them but a lot of them died and didn't lure them to the next line of cage traps. SO then I had my civilians pick up the stuff in the corridor and they lured them in.
Now to my topic. The caged goblins I took their stuff away and everything, and had my dwarves send them to the pit (with the troglodytes, heh heh heh.)
I sent one of them and that worked, and then I sent the rest.
This then sort of started a chain reaction
Urist McDwarf cancels Pit/Pond large creature: Interrupted by Goblin Spearman
Once they get interrupted, (by animals IN THE PIT) they lose the creature for a bit and then change their task to Handle Large Creature.
Well now due to that second they lose the creature they interrupt the 6 other goblin haulers and the process repeats (and it still is!)
One more goblin got into the pit but the rest are still being "handled"
and for some reason they cancel the handle large creature because they need an empty cage?
Anyways, just as a warning to everyone, pit your prisoners ONE AT A TIME. Otherwise FUN may ensue.
I am just waiting for one of these handlers to die of thirst. Thankfully people keep switching off the labour to another dwarf, though I think when one person went to seek an infant a goblin may have gotten away.
So I'll inform you later if they get all of them in the pit (or if they all escape), but for now my dwarves are stuck square dancing with their naked goblin partners.