pywsgi.py: do not log if the socket is set None (for websocket)

gevent/pywsgi.py

@@ -432,6 +432,7 @@ class WSGIHandler(object):
                 self.result.close()
             self.wsgi_input._discard()
             self.time_finish = time.time()
+            if self.socket is not None:
                 self.log_request()
 
     def get_environ(self):