b09a941 py3: cainstance: fix BytesWarning

Authored and Committed by mbasti 6 years ago
    py3: cainstance: fix BytesWarning
    
    https://fedorahosted.org/freeipa/ticket/4985
    
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>