title: Elasticsearch bool must_not doesn't work with multi-fields.
body: <p>I use multi-fields <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/_multi_fields.html" rel="nofollow">https://www.elastic.co/guide/en/elasticsearch/reference/current/_multi_fields.html</a></p>
  
  <p>Here is part of my mapping:</p>
  
  <pre><code>...
  "Diagnosis": {
                 "type": "string",
                 "fields":{
                   "not_analyzed":{
                      "type":"string",
                      "index":"not_analyzed"
                   }
                  }
              }
  ...
  </code></pre>
  
  <p>I run this query:</p>
  
  <pre><code>curl -XGET 'elasticsearch_server:9200/db-index/Diagnosis/_search?pretty' -d '{"query": {"bool": {"must_not": [{"match": {"Diagnosis.not_analyzed": "F06.4 - Organic anxiety disorder"}}], "must": [{"match": {"Diagnosis": "Dementia disease disorder"}}]}}}'
  </code></pre>
  
  <p>Despite the must_not clause the query above returns "<strong>F06.4 - Organic anxiety disorder</strong>" string amid other results.</p>
  
  <p>I can exclude all results with 'anxiety' word doing this </p>
  
  <pre><code>curl -XGET 'elasticsearch_server:9200/db-index/Diagnosis/_search?pretty' -d '{"query": {"bool": {"must_not": [{"match": {"Diagnosis": "anxiety"}}], "must": [{"match": {"Diagnosis": "Dementia disease disorder"}}]}}}'
  </code></pre>
  
  <p>But the goal is to exclude only the exact string "<strong>F06.4 - Organic anxiety disorder</strong>" from results.
  How can I do that?</p>