WordPress Multisite Network Doesn't Work

Using the helper to install WordPress in Google App Engine and then [creating a Multisite Network](https://wordpress.org/support/article/create-a-network/) using sub-directories.

This has a couple of major issues in wp-admin for any site that's not the main network site:

1. The network admin dashboard at https://example.appspot.com/wp-admin/network/ loads the front-end theme's index.php.

2. The admin dashboard for any network site has a redirect loop i.e https://example.appspot.com/new-network-site-name/wp-admin/

As far as I can tell, this has something to do with the get_real_file_to_load() function in [gae-app.php](https://github.com/GoogleCloudPlatform/php-tools/blob/master/src/Utils/WordPress/files/gae-app.php) not supporting WordPress multisite?