source3/libads/kerberos.c:kerb_prompter causes problems when net ads join -k used in a script and the password has expired

[Richard Sharpe]

Hi folks,

At least on FreeBSD it seems that net ads join -k -Uuser%password
causes a high-CPU-usage infinite loop when the password has expired.

It seems that perhaps there should be a check to see if stdin is not a
tty and return a KRB5 error rather than success if is not a tty.

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)