LUCENE-6303: Do not cache filters twice in SolrIndexSearcher.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1662914 13f79535-47bb-0310-9956-ffa450edef68

solr/core/src/java/org/apache/solr/search/SolrIndexSearcher.java

@@ -301,6 +301,9 @@ public class SolrIndexSearcher extends IndexSearcher implements Closeable,SolrIn
       fieldNames.add(fieldInfo.name);
     }
 
+    // We already have our own filter cache
+    setQueryCache(null);
+
     // do this at the end since an exception in the constructor means we won't close    
     numOpens.incrementAndGet();
   }