Substituting a custom User model doesn't use get_user_model() properly

[hgezim]

In the ​Substituting a custom User model section of the documentation, ​A full example subsection imports the custom user model as such:

from customauth.models import MyUser

instead stead of using get_user_model() from django.contrib.auth.

[Russell Keith-Magee]

In this case, importing the actual model is correct. The import is occurring in the admin definition file, which is setting up the admin for MyUser. This admin definition will *only* work for MyUser, so we're not looking to exploit flexible model definitions; if you're not using MyUser, you won't be using this admin definition.

Additional proof of this -- get_user_model() calls shouldn't be made at the module level, which would be required in order to set up the UserChangeForm and UserCreationForm.