Refs #30557 -- Fixed crash of ordering by ptr fields when Meta.ordering contains F() expressions.

Thanks Can Sarıgöl for the report.

Follow up to 8c5f9906c5.

tests/ordering/models.py

@@ -33,7 +33,7 @@ class Article(models.Model):
     class Meta:
         ordering = (
             '-pub_date',
-            'headline',
+            models.F('headline'),
             models.F('author__name').asc(),
             OrderBy(models.F('second_author__name')),
         )