bpo-40275: Adding threading_helper submodule in test.support (GH-20263)

diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
index f68af52..79f702d 100644
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -16,6 +16,7 @@
 import contextlib
 from test import support
 from test.support import socket_helper
+from test.support import threading_helper
 from test.support import ALWAYS_EQ, LARGEST, SMALLEST
 
 try:
@@ -1464,7 +1465,7 @@
         self.assertTrue(server.use_builtin_types)
 
 
-@support.reap_threads
+@threading_helper.reap_threads
 def test_main():
     support.run_unittest(XMLRPCTestCase, HelperTestCase, DateTimeTestCase,
             BinaryTestCase, FaultTestCase, UseBuiltinTypesTestCase,