管道超级代理响应到快速响应

我正在尝试使用 Express 应用程序“代理”一些文件。为什么下面的代码不起作用？

var app = require('express')()
var request = require('superagent')
app.get('/image', function(req, res, next) {
  request('http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG')
    .then(function(_res) {
      _res.pipe(res)
    })
})

app.listen(3001, function() {
  console.log('listen')
})

当我直接“wget”一个文件时，它可以工作：

$ wget http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG
--2016-07-20 11:44:33--  http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG
Resolving s3.amazonaws.com... 54.231.120.106
Connecting to s3.amazonaws.com|54.231.120.106|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 21026 (21K) [image/jpeg]
Saving to: 'huge.104.520060.JPG'

huge.104.520060.JPG                           100%[==============================================================================================>]  20.53K  --.-KB/s    in 0.1s

2016-07-20 11:44:34 (203 KB/s) - 'huge.104.520060.JPG' saved [21026/21026]

当我调用我的 enpdpoint 时，它永远不会完成：

$ wget localhost:3001/image
--2016-07-20 11:45:00--  http://localhost:3001/image
Resolving localhost... 127.0.0.1, ::1
Connecting to localhost|127.0.0.1|:3001... connected.
HTTP request sent, awaiting response...

一些细节：

$ npm -v
3.9.5

$ npm list --depth=0
express-superagent-pipe-file
├── [email protected]
└── [email protected]

超级代理的响应对象不应被视为流，因为它可能已经是自动序列化的结果（例如从 JSON 到 JavaScript 对象）。不是使用响应对象，而是管道数据文档指出您可以直接将 superagent 请求传送到流：

var app = require('express')()
var request = require('superagent')
app.get('/image', function(req, res, next) {
  request('http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG')
    .pipe(res)
})

app.listen(3001, function() {
  console.log('listen')
})