New check introduced in Django sometime since 1.7.1 (tested with Django master 5b1fb0a75d6961d78ba68c72008f1cc535f9689a) which we need to fake for our purposes, because the model doesn't really exist usefully.
The ModelAdmin method was introduced in Django 504c89e8008c557a1e83c45535b549f77a3503b2, ticket is https://code.djangoproject.com/ticket/6327