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

diff --git a/Lib/test/test_socketserver.py b/Lib/test/test_socketserver.py
index c663cc9..5db8cec 100644
--- a/Lib/test/test_socketserver.py
+++ b/Lib/test/test_socketserver.py
@@ -14,8 +14,9 @@
 import socketserver
 
 import test.support
-from test.support import reap_children, reap_threads, verbose
+from test.support import reap_children, verbose
 from test.support import socket_helper
+from test.support import threading_helper
 
 
 test.support.requires("network")
@@ -120,7 +121,7 @@
         self.assertEqual(server.server_address, server.socket.getsockname())
         return server
 
-    @reap_threads
+    @threading_helper.reap_threads
     def run_server(self, svrcls, hdlrbase, testfunc):
         server = self.make_server(self.pickaddr(svrcls.address_family),
                                   svrcls, hdlrbase)
@@ -249,7 +250,7 @@
                         socketserver.DatagramRequestHandler,
                         self.dgram_examine)
 
-    @reap_threads
+    @threading_helper.reap_threads
     def test_shutdown(self):
         # Issue #2302: shutdown() should always succeed in making an
         # other thread leave serve_forever().