bpo-34136: Make test_do_not_recreate_annotations more reliable. (GH-8364)

Lib/test/test_opcodes.py

 # Python test set -- part 2, opcodes
 
 import unittest
-from test import ann_module
+from test import ann_module, support
 
 class OpcodeTest(unittest.TestCase):
 
@@ -42,10 +42,14 @@ class OpcodeTest(unittest.TestCase):
         self.assertEqual(ns['__annotations__'], {'x': int, 1: 2})
 
     def test_do_not_recreate_annotations(self):
+        annotations = {}
+        # Don't rely on the existence of the '__annotations__' global.
+        with support.swap_item(globals(), '__annotations__', annotations):
             class C:
                 del __annotations__
-            with self.assertRaises(NameError):
-                x: int
+                x: int  # Updates the '__annotations__' global.
+        self.assertIn('x', annotations)
+        self.assertIs(annotations['x'], int)
 
     def test_raise_class_exceptions(self):