The user table is not dumped by that tool. The warning notice makes it clear
and will avoid someone having some trouble recovering his precious private
data.
XML output is sent to stdout; progress reports are sent to stderr.
+WARNING: this is not a full database dump! It is merely for public export
+ of your wiki. For full backup, see our online help at:
+ https://www.mediawiki.org/wiki/Backup
+
Usage: php dumpBackup.php <action> [<options>]
Actions:
--full Dump all revisions of every page.