Not so much a bug as a behavioral error. Generally with the group AI, monsters that have it will feel free to charge @ when @ is in a room but will shy away when @ is in a corridor. Makes sense. However, this breaks down if @ is in the moat of a moated room (in essence, a corridor). Then the monsters will go after @ as if @ was in an open room. Monsters treat moated rooms as open rooms allowing @ to exploit the group AI.
I'm not sure it's even worth bothering to adjust. But in case someone decides to work on this in the future, this might be something to keep in mind.
I'm not sure it's even worth bothering to adjust. But in case someone decides to work on this in the future, this might be something to keep in mind.