[3.7] bpo-34136: Make test_do_not_recreate_annotations more reliable. (GH-8364) (GH-8365)

(cherry picked from commit 06ca3f0c09)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Lib/test/test_opcodes.py

@@ -1,7 +1,7 @@
 # Python test set -- part 2, opcodes
 
 import unittest
-from test import ann_module
+from test import ann_module, support
 
 class OpcodeTest(unittest.TestCase):
 
@@ -42,6 +42,9 @@ class OpcodeTest(unittest.TestCase):
         self.assertEqual(ns['__annotations__'], {'x': int, 1: 2})
 
     def test_do_not_recreate_annotations(self):
+        # Don't rely on the existence of the '__annotations__' global.
+        with support.swap_item(globals(), '__annotations__', {}):
+            del globals()['__annotations__']
             class C:
                 del __annotations__
                 with self.assertRaises(NameError):