If a long worm's head is on the drawbridge and a tail segment is at the
portcullis and you raise the drawbridge, bad monster handling occurs
because of some recursion that occurs before set_entity is called again.
Not sure when this last worked; it's broken in 3.4.2 as well. Modified
e_died to ensure both entity objects for the same monster get cleaned up
so subsequent e_at calls behave as expected.
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