关闭连接而不是设置'keep-alive'

我试图keep-alive在一个非常简单的express应用程序中禁用该设置.我尝试了在旧版本中做同样事情的人给出的答案:

var express = require('express');
var app = express();

app.get('/', function(req, res) {
    res.set('Connection', 'close'); // attempting to override default (keep-alive)
    res.set('Proof', 'close');      // just to show that this should modify the header value
    res.send('hello');
});

var server = app.listen(3000, function() {
    console.log('Listening on port %d', server.address().port);
});

但是,Connection仍然设置为keep-alive:

$ curl -D - http://my-test-site.com
HTTP/1.1 200 OK
Server: nginx/1.4.7
Date: Sun, 11 May 2014 08:07:51 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 5
Connection: keep-alive
X-Powered-By: Express
Proof: close
ETag: "907060870"

hello%

我怎样才能换keep-alive到close？

版本

节点0.10.8
表示4.1.1