[4.0.x] Fixed #33361 -- Fixed Redis cache backend crash on booleans.

Backport of 2f33217ea2 from main

django/core/cache/backends/redis.py

@@ -10,8 +10,14 @@ from django.utils.module_loading import import_string
 
 
 class RedisSerializer(PickleSerializer):
+    """
+    Similar to PickSerializer, except integers are serialized as native Redis
+    integers for better incr() and decr() atomicity.
+    """
     def dumps(self, obj):
-        if isinstance(obj, int):
+        # Only skip pickling for integers, a int subclasses as bool should be
+        # pickled.
+        if type(obj) is int:
             return obj
         return super().dumps(obj)
 

docs/releases/4.0.1.txt

@@ -12,3 +12,6 @@ Bugfixes
 * Fixed a regression in Django 4.0 that caused a crash of
   :meth:`~django.test.SimpleTestCase.assertFormsetError` on a formset named
   ``form`` (:ticket:`33346`).
+
+* Fixed a bug in Django 4.0 that caused a crash on booleans with the
+  ``RedisCache`` backend (:ticket:`33361`).

tests/cache/tests.py

@@ -411,17 +411,20 @@ class BaseCacheTests:
 
     def test_data_types(self):
         # Many different data types can be cached
-        stuff = {
+        tests = {
             'string': 'this is a string',
             'int': 42,
+            'bool': True,
             'list': [1, 2, 3, 4],
             'tuple': (1, 2, 3, 4),
             'dict': {'A': 1, 'B': 2},
             'function': f,
             'class': C,
         }
-        cache.set("stuff", stuff)
+        for key, value in tests.items():
-        self.assertEqual(cache.get("stuff"), stuff)
+            with self.subTest(key=key):
+                cache.set(key, value)
+                self.assertEqual(cache.get(key), value)
 
     def test_cache_read_for_model_instance(self):
         # Don't want fields with callable as default to be called on cache read
@@ -1785,6 +1788,11 @@ class RedisCacheTests(BaseCacheTests, TestCase):
     def test_get_client(self):
         self.assertIsInstance(cache._cache.get_client(), self.lib.Redis)
 
+    def test_serializer_dumps(self):
+        self.assertEqual(cache._cache._serializer.dumps(123), 123)
+        self.assertIsInstance(cache._cache._serializer.dumps(True), bytes)
+        self.assertIsInstance(cache._cache._serializer.dumps('abc'), bytes)
+
 
 class FileBasedCachePathLibTests(FileBasedCacheTests):
     def mkdtemp(self):