Cleanup this test's modification of os.environ in teardown (this already

exists in 3.4 but apparently wasn't done for 3.3).

Lib/test/test_urllib2_localnet.py

@@ -353,12 +353,15 @@ class TestUrlopen(unittest.TestCase):
     def setUp(self):
         super(TestUrlopen, self).setUp()
         # Ignore proxies for localhost tests.
+        self.old_environ = os.environ.copy()
         os.environ['NO_PROXY'] = '*'
         self.server = None
 
     def tearDown(self):
         if self.server is not None:
             self.server.stop()
+        os.environ.clear()
+        os.environ.update(self.old_environ)
         super(TestUrlopen, self).tearDown()
 
     def urlopen(self, url, data=None, **kwargs):