Some players of 3.6 recently noticed that sometimes, mimics in shops
seemed to have moved around even before the player had entered the shop
or done anything to uncloak them. I found that this was because
finish_meating was being called for all non-eating monsters when
restoring a level (monsters that weren't eating anything would have
meating == 0 so always pass the 'imv > meating' check). This would
uncloak mimics -- but not all the time, because the 'mappearance != 0'
test meant mimics disguised as strange objects weren't uncloaked. I
think that was meant to be an additional check to confirm the monster
really did have a disguise, but in reality it meant that M_AP_OBJECT
"strange object", M_AP_MONSTER "giant ant", etc disguises wouldn't be
removed by finish_meating.
As it turns out, this was mostly fixed by coincidence in 221e4a7, which
fixed the "exclude actual mimics" check in finish_meating. So at this
point in 3.7 it's largely a latent bug, but it still had the potential
to improperly uncloak non-mimics who can disguise themselves (like the
Wizard of Yendor, maybe?), and could cause other problems if
finish_meating were updated to have additional effects, or if some
monster types were made to disguise themselves as a strange object when
eating a mimic.
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