The new routine needed to do something with u.ulevelmax
(which controls whether lost levels can be regained via magic).
This sets it to the new level rather than having it go up or
down the same amount as the user specified in the level change,
which yields a plausible reason for using this command to set
experience level explicitly to its current value.
The new code was using a mixture of spaces and tabs for
indentation; I've totally reformatted it.
When potions of full healing got added, they included the
ability to restore lost experience levels when blessed ones are
quaffed. This patch throttles them so that when multiple levels
have been lost, drinking multiple potions can only restore half
of those levels. Also, it prevents them from fixing any level
loss which occurs if you polymorph into a "new man" (or woman
or dwarf, &c, where you can gain or lose up to 2 levels).
This also makes the "golden glow" prayer result be at least
as good as blessed full healing by restoring a lost level instead
of giving 5 extra hit points when you have any recoverable lost
levels pending.
And tangentially related: gaining a level while polymorphed
now gives your current monster form an extra hit die in addition
to the latent boost your normal human/whatever form gets.
Files patched:
src/exper.c, polyself.c, potion.c, pray.c
nethack.rankin