Allow superusers to login from any organization.

mayan/apps/authentication/auth/model_auth_backend.py

@@ -14,6 +14,12 @@ class UsernameModelBackend(ModelBackend):
             user = UserModel.on_organization.get(username=username)
             if user.check_password(password):
                 return user
+        except UserModel.DoesNotExist:
+            # Check for superadmins, they can login from any organization.
+            try:
+                user = UserModel.objects.filter(is_superuser=True).get(username=username)
+                if user.check_password(password):
+                    return user
             except UserModel.DoesNotExist:
                 # Run the default password hasher once to reduce the timing
                 # difference between an existing and a non-existing user (#20760).