return function (ContainerConfigurator $container, PhpFileLoader $loader) {
    $services = $container->services();
    $services->instanceof(SomeInterface::class)->tag('my_tag');

    // This import triggers a recursive load() on the same loader instance
    $loader->import('child.php');

    // The instanceof rules above are currently lost here because the 
    // child load() reset the state in its finally block.
    $services->set(MyService::class, MyService::class); 
};