title: Queries hang when using mongoose.createConnection() vs mongoose.connect()
body: <p>Works:</p>
  
  <pre><code>var mongoose = require('mongoose');
  
  var db = function() {
    return {
      config: function(conf) {
        mongoose.connect('mongodb://' + conf.host + '/' + conf.database);
        var db = mongoose.connection;
        db.on('error', console.error.bind(console, 'connection error:'));
        db.once('open', function callback() {
          console.log('db connection open');
        });
      }
    };
  };
  
  module.exports = db();
  </code></pre>
  
  <p>Doesn't work:</p>
  
  <pre><code>var mongoose = require('mongoose');
  
  var db = function() {
    return {
      config: function(conf) {
        var db = mongoose.createConnection('mongodb://' + conf.host + '/' + conf.database);
        db.on('error', console.error.bind(console, 'connection error:'));
        db.once('open', function callback() {
          console.log('db connection open');
        });
      }
    };
  };
  
  module.exports = db();
  </code></pre>
  
  <p>Insert code:</p>
  
  <pre><code>'use strict';
  
  
  var mongoose = require('mongoose'),
  User = mongoose.model('User'),
  p = require('../lib/promise');
  
  ...
  app.post('/user', function (req, res) {
    res.format({
      json: function () {
        //extract the user from the req
        try {
          var user = new User();
          user.firstName = req.body.firstName;
          user.lastName = req.body.lastName;
          user.userName = req.body.userName;
          user.password = req.body.password;
          user.email = req.body.email;
  
          user.save(function(err, data) {
          //omitted
  ...
  </code></pre>