title: Elasticsearch MLT query returns no results unless you make criteria stricter
body: <p>I am posting the following query against the _explain endpoint of a document with "three" in the title field</p>
  
  <pre><code>{
  "query": {
      "bool": {
          "must": [
              {
                  "bool": {
                      "should": [
                          {
                              "more_like_this": {
                                  "min_doc_freq": 1,
                                  "fields": [
                                      "title"
                                  ],
                                  "max_query_terms": 10,
                                  "like": "Three Reasons Spice Girls Will Reunite (And Three Why They Won't)",
                                  "min_term_freq": 1
                              }
                          },
                          {
                              "more_like_this": {
                                  "min_doc_freq": 1,
                                  "fields": [
                                      "description"
                                  ],
                                  "max_query_terms": 10,
                                  "like": "Three Reasons Spice Girls Will Reunite (And Three Why They Won't)",
                                  "min_term_freq": 1
                              }
                          }
                      ]
                  }
              }
          ]
      }
  }
  </code></pre>
  
  <p>}</p>
  
  <p>The response/explanation I get:</p>
  
  <pre><code>"matched": false,
  "explanation": {
      "value": 0,
      "description": "Failure to meet condition(s) of required/prohibited clause(s)",
      "details": [
          {
              "value": 0,
              "description": "no match on required clause (((title:girl title:and title:why title:will title:thei title:won title:reason title:reunit title:spice title:three)~3) ((description:and description:why description:thei description:won description:girl description:will description:reason description:spice description:reunit description:three)~3))",
              "details": [
                  {
                      "value": 0,
                      "description": "No matching clauses",
                      "details": []
                  }
              ]
          },
          {
              "value": 0,
              "description": "match on required clause, product of:",
              "details": [
                  {
                      "value": 0,
                      "description": "# clause",
                      "details": []
                  },
                  {
                      "value": 0.023566995,
                      "description": "_type:media, product of:",
                      "details": [
                          {
                              "value": 1,
                              "description": "boost",
                              "details": []
                          },
                          {
                              "value": 0.023566995,
                              "description": "queryNorm",
                              "details": []
                          }
                      ]
                  }
              ]
          }
      ]
  }
  </code></pre>
  
  <p>However, if I increase either min_term_freq from 1 to 2, I get a match. Similarly, I get a match if I remove several terms from the like query, for example "Three Reasons Spice (And Three)". </p>
  
  <p>Why does this make sense that it would match as the criteria gets more strict (min_term_freq increases)</p>