Spotted in production:
Warning: Revision::ensureTitle: Could not determine title for page ID 47342037 and revision ID 673119728 [Called from Revision::ensureTitle in /srv/mediawiki/php-1.31.0-wmf.20/includes/Revision.php at line 564] in /srv/mediawiki/php-1.31.0-wmf.20/includes/debug/MWDebug.php on line 309
On wmf.17 too