Currently php maintenance/run.php CentralAuth:migratePass0 fails with Fatal error: Cannot declare class MigratePass0, because the name is already in use in […]/extensions/CentralAuth/maintenance/migratePass0.php on line 18.
This is due to CentralAuth's extension.json declaring "MediaWiki\\Extension\\CentralAuth\\Maintenance\\": "maintenance/" in AutoloadNamespaces. Thus calling php maintenance/run.php CentralAuth:migratePass0 will make MediaWiki try to autoload extensions/CentralAuth/maintenance/migratePass0.php looking for MediaWiki\Extension\CentralAuth\Maintenance\migratePass0 (which it doesn't contain). The subsequent loading of the same script in MaintenanceRunner::loadScriptFile will then error out as shown above.