Self test fails, probably due to sharding?

On our daily LTD:

1a60486d2be6:/var/www/html$ ./occ notify_push:self-test -vvv
✓ redis is configured
✓ push server is receiving redis messages

In JoinCondition.php line 129:
                                                                                
  [OC\DB\QueryBuilder\Partitioned\InvalidPartitionedQueryException]             
  join condition for filecache needs to explicitly refer to the table by alias  
                                                                                

Exception trace:
  at /var/www/html/lib/private/DB/QueryBuilder/Partitioned/JoinCondition.php:129
 OC\DB\QueryBuilder\Partitioned\JoinCondition::parseSubCondition() at /var/www/html/lib/private/DB/QueryBuilder/Partitioned/JoinCondition.php:81
 OC\DB\QueryBuilder\Partitioned\JoinCondition::parse() at /var/www/html/lib/private/DB/QueryBuilder/Partitioned/PartitionedQueryBuilder.php:217
 OC\DB\QueryBuilder\Partitioned\PartitionedQueryBuilder->join() at /var/www/html/lib/private/DB/QueryBuilder/Partitioned/PartitionedQueryBuilder.php:204
 OC\DB\QueryBuilder\Partitioned\PartitionedQueryBuilder->innerJoin() at /var/www/html/apps/notify_push/lib/SelfTest.php:225
 OCA\NotifyPush\SelfTest->getStorageIdForTest() at /var/www/html/apps/notify_push/lib/SelfTest.php:77
 OCA\NotifyPush\SelfTest->test() at /var/www/html/apps/notify_push/lib/Command/SelfTest.php:46
 OCA\NotifyPush\Command\SelfTest->execute() at /var/www/html/3rdparty/symfony/console/Command/Command.php:326
 Symfony\Component\Console\Command\Command->run() at /var/www/html/3rdparty/symfony/console/Application.php:1078
 Symfony\Component\Console\Application->doRunCommand() at /var/www/html/3rdparty/symfony/console/Application.php:324
 Symfony\Component\Console\Application->doRun() at /var/www/html/3rdparty/symfony/console/Application.php:175
 Symfony\Component\Console\Application->run() at /var/www/html/lib/private/Console/Application.php:187
 OC\Console\Application->run() at /var/www/html/console.php:90
 require_once() at /var/www/html/occ:33

notify_push:self-test

Start with apps/notify_push/lib/SelfTest.php around getStorageIdForTest() and its join at line 225, then read lib/private/DB/QueryBuilder/Partitioned/JoinCondition.php around line 129. Run occ notify_push:self-test -vvv to reproduce the InvalidPartitionedQueryException. Done means the self-test completes without the partitioned-query failure.