bpo-18799: Resurrect test_404 in test_xmlrpc. (GH-11196)

Lib/test/test_xmlrpc.py

@@ -818,11 +818,10 @@ class SimpleServerTestCase(BaseServerTestCase):
                 # protocol error; provide additional information in test output
                 self.fail("%s\n%s" % (e, getattr(e, "headers", "")))
 
-    # [ch] The test 404 is causing lots of false alarms.
-    def XXXtest_404(self):
+    def test_404(self):
         # send POST with http.client, it should return 404 header and
         # 'Not Found' message.
-        conn = httplib.client.HTTPConnection(ADDR, PORT)
+        conn = http.client.HTTPConnection(ADDR, PORT)
         conn.request('POST', '/this-is-not-valid')
         response = conn.getresponse()
         conn.close()