Running "php dump-tm.php --lang=nl --target=/home/siebrand/export/" on translatewiki.net I'm getting the following notice for every message group that is dumed:

PHP Notice: Undefined property: GettextFormatWriter::$owndata in /var/www/w/extensions/Translate/ffs/Gettext.php on line 98

Version: unspecified
Severity: normal