I experimented:
Requesting: http://www.kingdomofloathing.com/cellar.php?action=autofaucet
Retrieved: http://www.kingdomofloathing.com/cellar.php?action=autofaucet
Redirect to: choice.php?forceoption=1
Requesting: http://www.kingdomofloathing.com/choice.php?forceoption=1
Retrieved: http://www.kingdomofloathing.com/choice.php?forceoption=1
Redirect to: fight.php?ireallymeanit=1336056261
Requesting: http://www.kingdomofloathing.com/fight.php?ireallymeanit=1336056261
Retrieved: http://www.kingdomofloathing.com/fight.php?ireallymeanit=1336056261
... and we are finally in the fight.
In other words, there seems to be little benefit for KoLmafia to use "cellar.php?action=autofaucet"; it still redirects to choice.php and auto-selects option 1. I suppose that is one fewer server hit; we don't have to retrieve choice.php and then submit it again with the correct option chosen.
We should recognize this and log it correctly. And the "choice.php?forceoption=1" is new and should be recognized and logged correctly, I guess, although our usual mechanism of parsing the choice page to figure out which choice we were shunted to won't work.
This does not seem like a high priority. You want to fight lots of rats? Just do as I suggested for autoadventuring (which, unfortunately, will probably explore the rest of the cellar before going to the rat faucet; we could add a Tavern Cellar (Rat Faucet) adventure to force it) and you will squeeze out rats almost as efficiently, server-hit-wise, as using the link in the Relay Browser.