title: Arangodb Aql SORT not work for edge iteration
body: <p>I am try sort the result of edge iteration by 'beginAt' attribute but it don´t work for me
  follows the aql code:</p>
  
  <pre><code>FOR f IN TRAVERSAL(client, careerEdges, "client/100", "outbound", {paths:true})
  
              let sorted = (
                  FOR e IN f.path.edges
                      FILTER e.order &lt;= 3
              SORT e.beginAt DESC
              RETURN e)
  
  RETURN sorted
  </code></pre>
  
  <p>and the same to 'order' attribute. Always return the same sequence like this:</p>
  
  <pre><code>    [
    [],
    [
      {
        "_id": "careerEdges/240469605275",
        "_rev": "240469605275",
        "_key": "240469605275",
        "_from": "client/100",
        "_to": "careers/iniAlt",
        "order": 2,
        "$label": "noLonger",
        "beginAt": "2014-05-10 13:48:00",
        "endAt": "2014-07-20 13:48:00"
      }
    ],
    [
      {
        "_id": "careerEdges/240470064027",
        "_rev": "240470064027",
        "_key": "240470064027",
        "_from": "client/100",
        "_to": "careers/lidGru",
        "order": 3,
        "$label": "noLonger",
        "beginAt": "2014-07-20 13:48:00",
        "endAt": "2014-08-20 13:48:00"
      }
    ],
    [
      {
        "_id": "careerEdges/240469867419",
        "_rev": "240469867419",
        "_key": "240469867419",
        "_from": "client/100",
        "_to": "careers/iniEst",
        "endAt": null,
        "order": 1,
        "$label": "noLonger",
        "beginAt": "2014-06-10 13:48:00"
      }
    ]
  ]
  </code></pre>
  
  <p>My query is correctly? </p>