Imported custom user classes in tests depending on it

Without those imports, affected test files cannot be run
independently. Refs #21164.

django/contrib/auth/tests/test_decorators.py

@@ -1,6 +1,8 @@
 from django.conf import settings
 from django.contrib.auth import models
 from django.contrib.auth.decorators import login_required, permission_required
+# Trigger CustomUser perm creation:
+from django.contrib.auth.tests.custom_user import CustomUser
 from django.contrib.auth.tests.test_views import AuthViewsTestCase
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.core.exceptions import PermissionDenied

django/contrib/auth/tests/test_models.py

@@ -1,5 +1,6 @@
 from django.contrib.auth import get_user_model
 from django.contrib.auth.models import AbstractUser, Group, User, UserManager
+from django.contrib.auth.tests.custom_user import IsActiveTestUser1
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.core import mail
 from django.db.models.signals import post_save

django/contrib/auth/tests/test_views.py

@@ -21,6 +21,7 @@ from django.contrib.sessions.middleware import SessionMiddleware
 from django.contrib.auth import SESSION_KEY, REDIRECT_FIELD_NAME
 from django.contrib.auth.forms import (AuthenticationForm, PasswordChangeForm,
                 SetPasswordForm)
+from django.contrib.auth.tests.custom_user import CustomUser
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.contrib.auth.views import login as login_view