A reddit thread about an unaligned altar in an aligned temple was
a tipoff that mimics posing as altars didn't have any particular
alignment. The look-at code was misusing an operloaded field of the
underlying terrain. Pick an alignment at random when taking on the
appearance of an altar, store it in the mimic's mon->mextra->mcorpsenm
field, and have look-at use that.
Also, dropping a ring of polymorph into a sink can transform it, and
one possible outcome is an altar. In this case, the alignment is
part of the location's topology, but code setting that up was using
Align2amask(rn2(foo)). That's a macro which evaluates its argument
more than once. The first evaluation was effectively a no-op. If
the second evaluation picked lawful then the result was lawful as
intended. But if the second picked non-lawful and the third picked
lawful, the result would end up as none-of-the-above (a value of 3
when it needs to be a single-bit mask of 1, 2, or 4).
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