Speed up test_httpservers by avoiding a one-second cleanup wait after each test case.
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
index d78ae9a..d9e4063 100644
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -62,6 +62,7 @@
 
     def tearDown(self):
         self.thread.stop()
+        self.thread = None
         os.environ.__exit__()
         support.threading_cleanup(*self._threads)