In the Proximity Caves, the occasional N-01 Spotter can drop parts when destroyed.
Given that all other drones i can remember don't drop parts, and that Target Drones received a bugfix because they could drop parts, i assume this is a bug?
Here's a relevant excerpt from my current run's log :
31799_ Sneak attack on N-01 Spotter.
31799_ Destroyed Lgt. Ion Engine.
31799_ N-01 Spotter destroyed. // N-01 Spotter destroyed
31801_ Acquired 11 matter.
31811_ Hover Unit fries itself beyond repair. // N-01 Spotter part fries
31817_ Adv. Visual Processing Unit fries itself beyond repair. // N-01 Spotter part fries
I'd seen it before, but it's only this time that i realized this was probably a bug.