Issue #23027: test_warnings now passes all tests when run it with -Werror.

Lib/test/test_warnings.py

@@ -456,6 +456,9 @@ class WarnTests(BaseTest):
         self.assertIn('category must be a Warning subclass, not ',
                       str(cm.exception))
 
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.resetwarnings()
+            self.module.filterwarnings('default')
             with self.assertWarns(MyWarningClass) as cm:
                 self.module.warn('good warning category', MyWarningClass)
             self.assertEqual('good warning category', str(cm.warning))