title: Ember Data Store Find returns empty content on second call
body: <p>I have a model with a Fixtures data set, so no backend involved in here. For the model, I have 22 data records. When I query it for the first time in my IndexRoute, all 22 data records are returned. No problem here.</p>
  
  <p>When I leave the route, and come back later, the model hook of my IndexRoute is called again, but this time the same query does not return data.</p>
  
  <p>My Model hook looks like:</p>
  
  <pre><code>model: function () {
      var placeId = 0;
  
      console.log('Index Route: Model Hook');
      console.log('Getting hints for place ' + placeId);
  
      this.get('store').find('hint', { place: placeId })
          .then(
              function (hints) {
                  console.log('Found hints', hints.get('content'));
              }
          );
  
      return this.get('store').find('hint', { place: placeId });
  }
  </code></pre>
  
  <p>As you can see, for demo purposes I always query hints with place id equal to zero. As already said, the first time it returns the data (and I can see the data in the Chrome Ember Inspector), but the second time I enter this route does not return the data (which I know is out there).</p>
  
  <p>Edit:
  My hint model looks basically like</p>
  
  <pre><code>App.Hint = DS.Model.extend({
      title: DS.attr('string'),
      // some basic boring attributes
      place: DS.belongsTo('place', { async: true }) // Association with my Place Model
  });
  
  App.Place = DS.Model.extend({
      title: DS.attr('string'),
      // some more attributes
      hints: DS.hasMany('hint', { async: true })
  });
  </code></pre>
  
  <p>So the query <code>{place: placeId}</code> simply gets all those hints who have an association with a specific place. The problem is not that the query does not work - it works the first time the Index Route is triggered (and it works as I expect it to work). The problem is that all subsequent calls of index route, and all other locations that are trying to access hints, do not work anymore and always return an empty set.</p>