retrieving element hangs when containing window is closed

package.json

{
  "name": "bid",
  "version": "0.0.0",
  "description": "ERROR: No README.md file found!",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": "",
  "author": "",
  "license": "BSD",
  "devDependencies": {
    "wd": "0.0.26",
    "request": "~2.12.0",
    "underscore": "~1.4.2",
    "async": "~0.1.22"
  }
}

testcase.js

var request = require('request'),
    _ = require('underscore'),
    async = require('async');

//
// method used in wd to clean Selenium responses
//
var strip = function strip(str) {
  if(typeof(str) !== 'string') { return str; }
  var x = [];
  _(str.length).times(function(i) {
    if (str.charCodeAt(i)) {
      x.push(str.charAt(i));
    }
  });
  return x.join('');
};

var urlBase = 'http://localhost:4444/wd/hub';

var getOpts = {
  method: 'GET',
  Connection: 'keep-alive',
  headers: {
     Accept: 'application/json',
  }
};

var postOpts = _(getOpts).clone();
postOpts.method = 'POST';
postOpts.headers['Content-Type'] = 'application/json; charset=UTF-8';

var sessionId, buttonEl, fooEl; 

async.series([
  function(done) {
    //
    // Opening session
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session';
    
    data = {
      desiredCapabilities:{
        browserName: 'firefox'
        , version: ''
        , javascriptEnabled: true
        , platform: 'ANY'
      }
    };
    httpOpts.body = JSON.stringify(data);
    request( httpOpts, function(err, res, body) {
      var locationArr = res.headers.location.split('/');
      sessionId = locationArr[locationArr.length - 1];
      console.log("sessionId:", sessionId);
      done(err); 
    });
  },
  function(done) {
    //
    // Setting implicit wait to 5000
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/timeouts/implicit_wait';
    data = {
      ms: 5000
    };
    httpOpts.body = JSON.stringify(data);
    request( httpOpts, function(err, res, body) {
      done(err);
    });
  },
  function(done) {
    //
    // Navigating to url
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/url';
    
    data = {
      url: 'http://people.mozilla.org/~lhilaiel/hang/'
    };
    httpOpts.body = JSON.stringify(data);
    request( httpOpts, function(err, res, body) {
      done(err);
    });
  },
  function(done) {
    //
    // Getting button element
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/element';
    
    data = {
      using: 'id',
      value: 'theButton'
    };
    httpOpts.body = JSON.stringify(data);   
    request( httpOpts, function(err, res, body) {
      body = JSON.parse(strip(body));
      buttonEl = body.value.ELEMENT;
      done(err);
    });
  },
  function(done) {
    //
    // Clicking button to open popup
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/element/' 
      + buttonEl + '/click';
    
    data = {};
    httpOpts.body = JSON.stringify(data);
    request( httpOpts, function(err, res, body) {
      done(err);
    });
  },
  function(done) {
    //
    // Going into popup
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/window';
    
    data = {
      name: 'mypopup'
    };
    httpOpts.body = JSON.stringify(data);   
    request( httpOpts, function(err, res, body) {
      done(err);
    });
  },
  function(done) {
    //
    // Selecting existing element in popup  => OK
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/element';
    
    data = {
      using: 'id',
      value: '#foo'
    };
    httpOpts.body = JSON.stringify(data);   
    request( httpOpts, function(err, res, body) {
      body = JSON.parse(strip(body));
      fooEl = body.value.ELEMENT;
      done(err);
    });
  },
  function(done) {
    //
    // Selecting not-existing element in popup  => Not OK
    //
    var httpOpts = _(postOpts).clone();
    httpOpts.url = urlBase + '/session/' + sessionId + '/element';
    
    data = {
      using: 'id',
      value: 'foo'
    };
    httpOpts.body = JSON.stringify(data);   
    request( httpOpts, function(err, res, body) {
      console.log("You'll see this whenever"); // It hangs in there forever
      done(err);
    });
  }
], function(err) {
  if(err) { console.log(err); }
  //
  // quit
  //
  console.log('quitting');
  var httpOpts = {};
  httpOpts.method = 'DELETE';
  httpOpts.url = urlBase + '/session/' + sessionId;
  request(httpOpts, function(err) {});
});