'Called when we try to register or change to an illegal nickname.
The server should send this reply when the nickname contains any
disallowed characters.  The bot will stall, waiting for RPL_WELCOME, if
we don\'t handle this during sign-on.
@note: The method uses the spelling I{erroneus}, as it appears in
the RFC, section 6.1.'

def irc_ERR_ERRONEUSNICKNAME(self, prefix, params):

    if (not self._registered):
        self.setNick(self.erroneousNickFallback)
