title: Elasticsearch 'must' query with multiple criteria
body: <p>Trying to get python-elasticsearch or curl to return the appropriate results when using bool and must queries.</p>
  
  <p>I know the document is in my query, I can find it with 'should'; however, I need both criteria to be satisfied so I try to do the same query with 'must'.  When I use 'must' the document in question is not returned.</p>
  
  <p><strong>With Should</strong></p>
  
  <pre><code>$ curl -XGET 'localhost:9200/polarion/subtype1/_search?pretty' -H 'Content-Type: application/json' -d'
  {
     "query" : {
        "constant_score" : {
           "filter" : {
              "bool" : {
                "should" : [
                   { "term" : {"project" : "AMQ"}},  
                   { "term" : {"test-type" : "functional"}}]
             }
           }
        }
     }
  }
  '
  
  "hits" : {
      "total" : 3,
      "max_score" : 1.0,
      "hits" : [
        {
          "_index" : "polarion",
          "_type" : "subtype1",
          "_id" : "AV3s-vbF8T4AI9Zj3GkM",
          "_score" : 1.0,
          "_source" : {
            "project" : "AMQ",
            "query" : "test-metrics",
            "test-type" : "functional",
            "2017-08-16" : 1916
          }
        },
  </code></pre>
  
  <p><strong>With Must</strong></p>
  
  <pre><code>$ curl -XGET 'localhost:9200/polarion/subtype1/_search?pretty' -H 'Content-Type: application/json' -d'
  {
     "query" : {
        "constant_score" : {
           "filter" : {
              "bool" : {
                "must" : [
                   { "term" : {"project" : "AMQ"}},  
                   { "term" : {"test-type" : "functional"}}]
             }
           }
        }
     }
  }
  '
  
  
  {   "took" : 0,   "timed_out" : false,   "_shards" : {
      "total" : 5,
      "successful" : 5,
      "failed" : 0   },   "hits" : {
      "total" : 0,
      "max_score" : null,
      "hits" : [ ]   } }
  </code></pre>