def on_failed_login(self, subject, authc_token, ae):
self.forget_identity(subject)<EOL>
Reacts to a failed login by immediately forgetting any previously
remembered identity.  This is an additional security feature to prevent
any remenant identity data from being retained in case the
authentication attempt is not being executed by the expected user.

:param subject: the subject which executed the failed login attempt
:param authc_token:   the authentication token resulting in a failed
                      login attempt - ignored by this implementation
:param ae:  the exception thrown as a result of the failed login
            attempt - ignored by this implementation