Stopped using django.utils.unittest in the test suite.

Refs #20680.

tests/model_inheritance_regress/tests.py

@@ -5,10 +5,10 @@ from __future__ import absolute_import, unicode_literals
 
 import datetime
 from operator import attrgetter
-from django import forms
+from unittest import expectedFailure
 
+from django import forms
 from django.test import TestCase
-from django.utils.unittest import expectedFailure
 
 from .models import (Place, Restaurant, ItalianRestaurant, ParkingLot,
     ParkingLot2, ParkingLot3, Supplier, Wholesaler, Child, SelfRefParent,