Something I noticed during a level change in slash'em:
You hear the sounds of civilization. You fly down the stairs.
The first message ought to follow the second. Our only arrival messages
that are handled via the special level loader occur in the endgame where
travel is by magic portal, and the transit message given for portals is
for entering one rather than exiting at the far side, so this sequencing
problem can't currently be noticed in nethack. But sooner or later there
will be levels reachable by stairs and having entry messages, or there'll
be some feedback added when magic portal transport finishes, and then we'd
get bitten by this.
Tested by adding an arrival message to each of the bigroom variants.
projects / nethack / commit