Break infinite redirect loop
    
    When AUTH is set to fas, if the user has not sign the FPCA and tries
    accessing a page requiring authentication and FPCA, they get redirected
    to the index page, from there to the user's dashboard that requires
    authentication and FPCA and the loop is triggered.
    
    Fixes https://pagure.io/pagure/issue/3611
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>