Index: Lib/test/test_threading.py
===================================================================
--- Lib/test/test_threading.py	(revision 86050)
+++ Lib/test/test_threading.py	(working copy)
@@ -448,6 +448,7 @@
         self.assertEqual(data, "end of main\nend of thread\n")
         self.assertFalse(rc == 2, "interpreter was blocked")
         self.assertTrue(rc == 0, "Unexpected error")
+        p.stdout.close()
 
     def test_1_join_on_shutdown(self):
         # The usual case: on exit, wait for a non-daemon thread