fix bug of socket CLOSE_WAIT

lib/tunnel.js

@@ -138,20 +138,20 @@ TunnelingAgent.prototype.createSocket = function createSocket(options, cb) {
   function onConnect(res, socket, head) {
     connectReq.removeAllListeners();
     socket.removeAllListeners();
+    self.sockets[self.sockets.indexOf(placeholder)] = socket
 
     if (res.statusCode === 200) {
       assert.equal(head.length, 0);
       debug('tunneling connection has established');
-      self.sockets[self.sockets.indexOf(placeholder)] = socket;
       cb(socket);
     } else {
       debug('tunneling socket could not be established, statusCode=%d',
             res.statusCode);
       var error = new Error('tunneling socket could not be established, ' +
                             'statusCode=' + res.statusCode);
       error.code = 'ECONNRESET';
+      cb(socket)
       options.request.emit('error', error);
-      self.removeSocket(placeholder);
     }
   }