causes "dmonsfree: N removed doesn't match N+1 pending" warning. The
sandestin monster definition flags it as MR_STONE, immune to being
turned to stone. If the hero hit it with a cockatrice while it was
shape-changed into something which isn't MR_STONE, it had its mon->mhp
set to 0, so died, and its form (mon->data) was set back to sandestin.
known_hitum() decided that it didn't turn to stone because of MR_STONE
for that form so proceeded to kill it off due to lack of hit points,
causing it to die twice.
I started to change that so that it didn't kill off the critter a
second time, bit it really shouldn't be able to kill it by stoning in
the first place. So sandestin how shares some vampire code to revert
to innate form and not turn to stone when "killed" by stoning. It
only yields the normal visible polymorph message: "the <foo> turns
into a <bar>" without any attempt to explain why. Once in sandestin
form, smacking it with a cockatrice corpse doesn't do anything special
(due to MR_STONE now being unambiguously in effect). It will soon
shape-change to some other form and then become subject to being
forced back to innate shape by stoning again.