[krbdev.mit.edu #8309] ktadd gives unhelpful 'file not found' attempting to create keytab in unwritable directory

[Tom Yu via RT]

When either kadmin or kadmin.local ktadd attempts to create a new keytab
in a directory where the user has no write permission, it gives an
unhelpful 'file not found' message instead of a 'permission denied'
message.

In the following transcript, /tmp/x is not writable, and
/tmp/x/krb5.keytab doesn't exist.

kadmin.local:  ktadd -k /tmp/x/krb5.keytab host/jacobs-ladder.mit.edu
kadmin.local: Key table file '/tmp/x/krb5.keytab' not found while adding key to keytab

In the following transcript, KRB5_KTNAME is unset, and /etc/krb5.keytab
isn't writable.

kadmin.local:  ktadd host/jacobs-ladder.mit.edu
kadmin.local: Permission denied while adding key to keytab

This is probably actually a keytab library issue.