500 when using the Doppelgänger function in the Django Admin #1388

Traceback:

File "/usr/local/lib/python3.8/site-packages/django/contrib/auth/__init__.py" in login
  111.         backend = backend or user.backend

During handling of the above exception ('AnonymousUser' object has no attribute 'backend'), another exception occurred:

File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python3.8/site-packages/django/utils/decorators.py" in _wrapped_view
  142.                     response = view_func(request, *args, **kwargs)

File "/usr/local/lib/python3.8/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  44.         response = view_func(request, *args, **kwargs)

File "/usr/local/lib/python3.8/site-packages/django/contrib/admin/sites.py" in inner
  223.             return view(request, *args, **kwargs)

File "/usr/src/ep2021/assopy/admin.py" in create_doppelganger
  436.         auth.login(request, user)

File "/usr/local/lib/python3.8/site-packages/django/contrib/auth/__init__.py" in login
  117.             raise ValueError(

Exception Type: ValueError at /admin/auth/user/xxxx/login/
Exception Value: You have multiple authentication backends configured and therefore must provide the `backend` argument or set the `backend` attribute on the user.