'Called back when we are choosing a new password.  Get the old password
and send the authentication message with both.
@param np: the new password as entered by the user
@type np: L{bytes}'

def _setNewPass(self, np):

    op = self._oldPass
    self._oldPass = None
    self.askForAuth('password', (('\xff' + NS(op)) + NS(np)))
