diff -r 878dc9dfc565 Lib/test/test_urllib.py
--- a/Lib/test/test_urllib.py	Mon Jul 22 10:38:04 2013 +0200
+++ b/Lib/test/test_urllib.py	Mon Jul 22 20:28:14 2013 +1000
@@ -9,6 +9,7 @@
 import unittest
 from test import support
 import os
+import socket
 import sys
 import tempfile
 from nturl2path import url2pathname, pathname2url
@@ -1288,6 +1289,30 @@
             self.assertEqual(DummyURLopener().open(
                 "spam://c:|windows%/:=&?~#+!$,;'@()*[]|/path/"),
                 "//c:|windows%/:=&?~#+!$,;'@()*[]|/path/")
+            
+    def test_timeout(self):
+        # regression tests to ensure that adding a default value
+        # for Request.timeout doesn't break the OpenerDirector - issue 4079
+
+        # dummy handler that returns the Request.timeout as the response code
+        # in order to verify that it got down to the handler
+        class DummyHandler(urllib.request.BaseHandler):
+            def spam_open(self, req):
+                return urllib.response.addinfourl(io.StringIO("spam"), 
+                    None, req.full_url,
+                    req.timeout)
+
+        # test that default timeout using OpenerDirector is sane
+        opener = urllib.request.build_opener(DummyHandler())
+        v = opener.open('spam://example')
+        self.assertEqual(v.code, socket._GLOBAL_DEFAULT_TIMEOUT)
+
+        # test that when setting the timeout using OpenerDirector.open
+        # the timeout is passed down to the handler
+        timeout_override = 10
+        v = opener.open('spam://example', timeout=timeout_override)
+        self.assertEqual(v.code, timeout_override)
+
 
 # Just commented them out.
 # Can't really tell why keep failing in windows and sparc.
@@ -1375,6 +1400,7 @@
         Request = urllib.request.Request
         request = Request("http://www.python.org")
         self.assertEqual(request.get_method(), 'GET')
+        self.assertEqual(request.timeout, socket._GLOBAL_DEFAULT_TIMEOUT)
         request = Request("http://www.python.org", {})
         self.assertEqual(request.get_method(), 'POST')