Disabling couchdb signup (senile edition)

I’m already old enough to have a really bad memory (just got my retirement visa, mind you), but this is ridiculous: I’m installing a plain-vanilla-apt-get couchdb, add a few users, give them roles, and then I get to the point where I want to disable signups. Sure I can dive into the validate_doc_update() at the _users db, stress my feeble mind out and figure out what to change there, but since this is a security issue, I’d rather do this by the book. The only question is, of course, where’s the book? Turns  out I wrote it 🙂