title: Solr Boolean query on multi-valued field in filter query
body: <p>We have a multi-valued indexed field named <code>tags</code>. We want to find all documents that meet one of the following conditions via a filter query:</p>
  
  <ul>
  <li>if tag <code>flagged</code> is present, then tag <code>safe</code> should also be present.</li>
  <li>tag <code>flagged</code> is not present.</li>
  </ul>
  
  <p>I tried <code>fq=(tags:(flagged AND safe) OR -tags:flagged)</code> but it is not returning the desired results. Instead it is returning documents tagged<code>safe</code> and not tag <code>flagged</code> i.e. the result is same as this query: <code>fq=(tags:safe AND -tags:flagged)</code>. How do I fix my query?</p>
  
  <p>Also both <code>fq=(tags:safe AND -tags:flagged)</code> and <code>fq=(tags:safe OR -tags:flagged)</code> are returning the same results. Why is this?</p>
  
  <p>Solr version: 3.6.2</p>