Router register viewset with empty string as prefix conflicts with other viewsets

[arsanysamuel]

I have 2 viewsets that I want to register with a router, one should be accessed using the root path of the router and the other should have a prefix.

urls.py

urlpatterns = [
    re_path(r"^main/", include(router.urls)),
]

routers.py

router = DefaultRouter()
router.register(r"", MainViewSet, basename="main")
router.register(r"sub", SecondViewSet, basename="sub")

main/ works fine but when I try to access main/sub/ it returns 404, it only works when I populate the prefix string as follows:

router.register(r"main", MainViewSet, basename="main")

Then I can access the main viewset using main/main/ and the second viewset using main/main/sub/ which is not the desired path, am I doing something wrong or it should work with an empty prefix?

NOTE: I'm using a main urls.py file in the main app which imports and adds the above urls.py