#240: disable threads in the random IndexSearcher from newSearcher for this test class

lucene/core/src/test/org/apache/lucene/search/TestTopFieldCollector.java

@@ -59,7 +59,8 @@ public class TestTopFieldCollector extends LuceneTestCase {
     }
     ir = iw.getReader();
     iw.close();
-    is = newSearcher(ir);
+    // cannot use threads with this IndexSearcher since some tests rely on no threads
+    is = newSearcher(ir, true, true, false);
   }
 
   @Override