The web updater uses updaters.inc, which require if needed
populateCategory.php, populateParentId.php, populateRevisionLength.php and populateLogSearch.php.
This used to be .inc before r63225. Since the .php have been ported to doMaintenance style (r54225), they use Maintenance.php, which exits if called from a web server.
Result of this, upgrading from old installs fails silently midway (the error message goes to stderr).
deleteDefaultMessages.php isn't affected since it directly calls the static reallyExecute()
1.16 doesn't seem affected.
Version: 1.17.x
Severity: blocker