[bug#3939] Fixed bug with authentication with a bad password

                if 'close' in self._server.conf.show(login)['tags']:

                    raise AuthenticationError('Account is closed')

        if role not in WelcomeHandler.ROLES:

            raise BadRoleError('%r is not a legal role' % role)

        if role is None:

            logging.info('New authentication from %s: failure',

                         login.encode('ascii', 'ignore'))

            raise AuthenticationError('Bad login/password')

        else:

            if role not in WelcomeHandler.ROLES:

                raise BadRoleError('%r is not a legal role' % role)

            # If authentication is a success, try to register the client:

            try:

                self._server.register(login, role, conn)