Update is broken

In a clean checkout:

1. Take the attached database dump file, unzip it and restore it to a database. This is two dumps, drupal-7.filled.standard_all.database.php.gz and drupal-7.all-disabled.database.php in an sql file.
2. Point a D7-style settings.php to it.
3. Add $settings['update_free_access'] = TRUE; to it. Back this file up.
4. Run D8 update.php
5. Observe white screen of death.
6. Restore the database.
7. Remove everything in sites/default/files
8. Restore settings.php.
9. Apply patch.
10. Observe update finishing.
11. Report back.

How on earth can the testbots pass? I presume it has something to do with $settings['update_free_access'] = TRUE;.