Allow kojiweb to proxy users obtained via different mechanisms
    
    This allows for users authenticated to the Koji Web interface via
    Kerberos to be proxied to the HUB using an SSL certificate and
    (in theory) vice versa though it's not clear why you'd want that.
    
    This is useful in environments where the owners of the Kerberos
    realm are not willing to create service accounts and export
    keytabs for them.
    
    Set WebAuth = kerberos to indicate that users are authenticated
    to the web via Kerberos. The existing config controls how kojiweb
    authenticates to the HUB.
    
    If using this, it is recommended to set
    
    LoginCreatesUser = Off
    
    in hub.conf, to avoid accidental creation of Koji accounts for
    users of the wider Kerberos realm.