I did actually try this just now, and I got

  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
  <title>500 Internal Server Error</title>
  <h1>Internal Server Error</h1>
  <p>The server encountered an internal error and was unable to complete your request.  Either the server is overloaded or there is an error in the application.</p>

It is possible I guess that the server is overloaded. I'd like to think that if someone registered my name, I'd get a better error. It does say I created an account, and it doesn't prompt me for credentials on the second try.

The account creation does not echo Username or Email, which is unusual for an account creation, and I think that Password should echo at least the \n even if the password is entered blind as customary.