From a bug report, if you move into lava, die,
and are life-saved or leave bones, your potions will remain intact,
whereas if you have fire resistance and survive, they'll be subjected to
destroy_item() and usually be destroyed (not always, because stacks of
more than 1 don't always destroy the whole stack). Also, wooden ring
will be destroyed even if it happens to be ring of fire resistance.
This addresses both of those bugs.
He also thought that all vulnerable armor should be destroyed rather
than just boots in the case where you have fire resistance and survive,
but I didn't change that. It is a little odd, but presumeably only your
feet are in lava at first (although later sinking further into lava
doesn't actually burn up any other stuff).
9cad308536