Fixed #29970, #30041 -- Made ModelBase.__new__() pass attrs without contribute_to_class() to type.__new__().

tests/model_inheritance/tests.py

@@ -181,18 +181,33 @@ class ModelInheritanceTests(TestCase):
     def test_init_subclass(self):
         saved_kwargs = {}
 
-        class A:
+        class A(models.Model):
             def __init_subclass__(cls, **kwargs):
                 super().__init_subclass__()
                 saved_kwargs.update(kwargs)
 
         kwargs = {'x': 1, 'y': 2, 'z': 3}
 
-        class B(A, models.Model, **kwargs):
+        class B(A, **kwargs):
             pass
 
         self.assertEqual(saved_kwargs, kwargs)
 
+    @unittest.skipUnless(PY36, '__set_name__ is new in Python 3.6')
+    @isolate_apps('model_inheritance')
+    def test_set_name(self):
+        class ClassAttr:
+            called = None
+
+            def __set_name__(self_, owner, name):
+                self.assertIsNone(self_.called)
+                self_.called = (owner, name)
+
+        class A(models.Model):
+            attr = ClassAttr()
+
+        self.assertEqual(A.attr.called, (A, 'attr'))
+
 
 class ModelInheritanceDataTests(TestCase):
     @classmethod