[3.0.x] Fixed #31538 -- Fixed Meta.ordering validation lookups that are not transforms.

Regression in 440505cb2cadbe1a5b9fba246bcde6c04f51d07e.

Thanks Simon Meers for the report.
Backport of b73e66e75802f10cc34d4880714554cea54dbf49 from master

1 files changed, 9 insertions, 0 deletions

diff --git a/tests/invalid_models_tests/test_models.py b/tests/invalid_models_tests/test_models.py
index 60b89b6f2e..8a204162d3 100644
--- a/tests/invalid_models_tests/test_models.py
+++ b/tests/invalid_models_tests/test_models.py
@@ -844,6 +844,15 @@ class OtherModelTests(SimpleTestCase):
         with register_lookup(models.CharField, Lower):
             self.assertEqual(Model.check(), [])
 
+    def test_ordering_pointing_to_lookup_not_transform(self):
+        class Model(models.Model):
+            test = models.CharField(max_length=100)
+
+            class Meta:
+                ordering = ('test__isnull',)
+
+        self.assertEqual(Model.check(), [])
+
     def test_ordering_pointing_to_related_model_pk(self):
         class Parent(models.Model):
             pass