Fixed #33626 -- Cleared cache when unregistering a lookup.

django/db/models/query_utils.py

@@ -217,6 +217,7 @@ class RegisterLookupMixin:
         if lookup_name is None:
             lookup_name = lookup.lookup_name
         del cls.class_lookups[lookup_name]
+        cls._clear_cached_lookups()
 
 
 def select_related_descend(field, restricted, requested, load_fields, reverse=False):

tests/custom_lookups/tests.py

@@ -323,6 +323,8 @@ class LookupTests(TestCase):
         with register_lookup(models.ForeignObject, Exactly):
             # getting the lookups again should re-cache
             self.assertIn("exactly", field.get_lookups())
+        # Unregistration should bust the cache.
+        self.assertNotIn("exactly", field.get_lookups())
 
 
 class BilateralTransformTests(TestCase):

tests/model_fields/test_jsonfield.py

@@ -88,7 +88,6 @@ class TestMethods(SimpleTestCase):
         transform = field.get_transform("my_transform")
         self.assertIs(transform, MyTransform)
         models.JSONField._unregister_lookup(MyTransform)
-        models.JSONField._clear_cached_lookups()
         transform = field.get_transform("my_transform")
         self.assertIsInstance(transform, KeyTransformFactory)