Attempt to fix a buglist item: if hero poly'd into iron golem form
enters a pool of water and drowning triggers reversion to human/whatever
form due to water damage, he will fall into that pool again, crawl or
teleport out, then redundantly crawl or teleport out for the initial entry.
[ spoteffects -> drown -> losehp -> rehumanize -> polyman -> spoteffects
-> drown ]
I don't have a lot of confidence in this fix. It does handle the
reported problem, and hasn't broken a couple of earlier tricky cases
(ice melting to water, land mine turning into a pit). But drown() and
lava_effects() seem to leave a trail of special case handling wherever
they appear so they--or spoteffects, or both--ought to be redone somehow.
a72e370899