Fixed #26986 -- Documented force_login() delegation to auth backends.

docs/releases/1.10.txt

@@ -827,6 +827,9 @@ Miscellaneous
 * In light of the previous change, the test client's
   :meth:`~django.test.Client.login()` method no longer always rejects inactive
   users but instead delegates this decision to the authentication backend.
+  :meth:`~django.test.Client.force_login()` also delegates the decision to the
+  authentication backend, so if you're using the default backends, you need to
+  use an active user.
 
 * :func:`django.views.i18n.set_language` may now return a 204 status code for
   AJAX requests.