Add a test case.

Author: ZeroIntensity

Lib/test/test_dict.py

@@ -1486,6 +1486,26 @@ def make_pairs():
                 self.assertEqual(d.get(key3_3), 44)
                 self.assertGreaterEqual(eq_count, 1)
 
+    def test_overwrite_managed_dict(self):
+        # GH-130327: Overwriting an object's managed dict incorrectly stored
+        # the new dictionary in the managed dict pointer for objects supporting
+        # inline values, leading to early clearing of the dictionary
+        import gc
+
+        class Shenanigans:
+            pass
+
+        to_be_deleted = Shenanigans()
+        to_be_deleted.attr = "whatever"
+        holds_reference = Shenanigans()
+        holds_reference.__dict__ = to_be_deleted.__dict__
+        holds_reference.ref = {"circular": to_be_deleted, "data": 42}
+
+        del to_be_deleted
+        gc.collect()
+        self.assertEqual(holds_reference.ref['data'], 42)
+        self.assertEqual(holds_reference.attr, "whatever")
+
 
 class CAPITest(unittest.TestCase):