pull up r18976 from trunk

pull up r18976 from trunk

 r18976@cathode-dark-space:  tlyu | 2006-12-18 23:16:22 -0500
 ticket: new
 status: open
 target_version: 1.6
 subject: don't pass null pointer to krb5_do_preauth_tryagain()

 	* src/lib/krb5/krb/get_in_tkt.c (krb5_get_init_creds): If
 	the error isn't PREAUTH_NEEDED and preauth_to_use is null, return
 	the error in err_reply, rather than attempting to pass a null
 	pointer to krb5_do_preauth_tryagain().

ticket: 5123
version_fixed: 1.6

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-6@19006 dc483132-0cff-0310-8789-dd5450dbe970