wrong doc message MediaWiki:Deletebatch-system-username
MediaWiki:Deletebatch-system-username "Delete page script"
Name of the system user account which can be used by privileged users (those who have the deletebatch-spoof user right) to delete pages. See also Right-deletebatch-spoof (« Pages supprimées par lots en tant que "suppression de page par script" »).
Message is speaking of script, documentation is speaking of system user account.