In confirming a previous bug, I stumbled upon some odd properties of room 80 that are obviously not intended, notably involving the direction you exit them.
Exiting west is impossible as that's the edge of the world and it's like walking into a brick wall. Exiting east places you in room 81 for real with music and dmap colors and everything, but there's no way to escape screens 80-87 so it's of no actual use, just detriment.
Exiting north uses a passageway/item room like transition always while exiting south always uses a cave style transition (in terms of how the screen fades out). The quest rule about music not restarting only works for exiting north; the music restarts when you exit south no matter what.
It would make much more sense and be more flexible to the player to cause all exit directions to act the same way and for the screen transition properties to be tied to the type of room (cave vs item cellar/passageway) not the direction of exit. The quest rule similarly should have universal behavior. I suppose it's not a really critical bug, but it's undesirable behavior at the very least.