Ticket 6 - Resource leak in systemd ask pass
    
    Bug Description:  In an error case, systemd would set the pin to "", which would
    leak the token memory.
    
    Fix Description:  strncpy the "" into the token to prevent the leak.
    
    https://pagure.io/svrcore/issue/6
    
    Author: wibrown
    
    Review by: nhosoi (Thanks!)