title: Node.js on('end') stream's listener fires twice
body: <p>It's a ordinary node practice, the on("end") callback fires twice per request even with using readable.once("end"). Here's tha code: </p>
  
  <pre><code>require("http").createServer(function (req, res) {
       var readable = require("fs").createReadStream("./image.jpg",{highWaterMark:1024*1024});
       readable.on("data", function (data) {
           res.write(data);
       })
  
      readable.on("end", function () {
          res.end()
          console.log("Ended");
      })
  
  }).listen(9000, function () {
      console.log("Listening.... on 9000");
  });
  </code></pre>