[SAMBA4] In Memory ccache doesn't work

[Love Hörnquist Åstrand]

> I just noticed that we always do the following before a
> krb5 authentification.
>
> AS-REQ without pre-auth krbtgt/REALM
> AS-REP error_code: KRB5KDC_ERR_PREAUTH_REQUIRED (25)
> AS-REQ with pre-auth krbtgt/REALM
> AS-REQ fine

The problem with sending a pre-auth is that is you guess wrong you
sometimes do not get back preauth-req but instead another error, and
that doesn't cause a retry.

> TGS-REQ for target principal
> TGS-REP fine
> TGS-REQ KDCOptions: 60000000 (Forwardable, Forwarded) for krbtgt/REALM
> TGS-REP error_code: KRB5KDC_ERR_BADOPTION (13)

I think the code tries to delegate, maybe it should check if the  
ticket is forwardable
before trying. (or not try to delegate in the first place).

Love