commit changes after doRandomForceMerge, or otherwise they're lost

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1607778 13f79535-47bb-0310-9956-ffa450edef68

lucene/test-framework/src/java/org/apache/lucene/index/RandomIndexWriter.java

@@ -364,6 +364,8 @@ public class RandomIndexWriter implements Closeable {
     // forceMerge since presumably they might open a reader on the dir.
     if (getReaderCalled == false && r.nextInt(8) == 2) {
       doRandomForceMerge();
+      // index may have changed, must commit the changes, or otherwise they are discarded by the call to close()
+      w.commit();
     }
     w.close();
   }