There was a very old bug, probably predating the OpenAdventure port,
that would poke a stashed value of -1 into the snake object if you did
a save in endgame, and then fail the savefile validation on resume.
This was masked for a long time by a bug in put() just fixed a couple
of revisions ago.
Turns out the code of put() had been modified ibcorrectly, but
the bug was masked in all but a few cases, noe of which would be
encountered in normal gameplay.
A test to ensure this bug does noit recur has been added.
