On mazelike levels, mimics will mimic either boulders or statues (of giant
ants, as it turns out). However, it does not make sense to mimic a boulder
on a hole or even a pit, since boulders would typically fall in. Also,
statues are not typical objects in Sokoban. So, skip statue special case
in Sokoban and always avoid the forced emulation of a boulder when on a
trap location outside a room. This is a bit drastic, but I couldn't think of
an argument for adding the code to do this only for pits, holes, et al,
which are the most likely traps outside rooms anyway.
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