Try to make this test more resistant to dropping from previous runs (ie, files that may exist but cause the test to fail).  Should be backported (assuming it works :-)
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 294ed5e..4851742 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -27,6 +27,7 @@
     def setUp(self):
         """Setup of a temp file to use for testing"""
         self.text = "test_urllib: %s\n" % self.__class__.__name__
+        test_support.unlink(test_support.TESTFN)
         FILE = file(test_support.TESTFN, 'wb')
         try:
             FILE.write(self.text)
@@ -195,6 +196,7 @@
     def test_copy(self):
         # Test that setting the filename argument works.
         second_temp = "%s.2" % test_support.TESTFN
+        test_support.unlink(second_temp)
         self.registerFileForCleanUp(second_temp)
         result = urllib.urlretrieve(self.constructLocalFileUrl(
             test_support.TESTFN), second_temp)
@@ -219,6 +221,7 @@
             self.assertEqual(count, count_holder[0])
             count_holder[0] = count_holder[0] + 1
         second_temp = "%s.2" % test_support.TESTFN
+        test_support.unlink(second_temp)
         self.registerFileForCleanUp(second_temp)
         urllib.urlretrieve(self.constructLocalFileUrl(test_support.TESTFN),
             second_temp, hooktester)