[krbdev.mit.edu #1488] Incorrect password error for principal with preauth is confusing

[Alexandra Ellwood via RT]

The error for an incorrect password for principal with preauth is
confusing.  krb5_init_creds_password returns KRB5KDC_ERR_PREAUTH_FAILED,
which translates to the string "Preauthentication failed".  So a typical
kinit where the user types a bad password goes as follows (this is with
a 1.2.x kinit):

dragon-slave% kinit preauth at TESTV5-KERBEROS-1.2.0
Password for preauth at TESTV5-KERBEROS-1.2.0: 
kinit(v5): Preauthentication failed while getting initial credentials

Needless to say, this is confusing and might dissuade the user from
trying to type their password again.