ignore engine closed exception as well

Author: kimchy

modules/elasticsearch/src/main/java/org/elasticsearch/index/shard/service/InternalIndexShard.java

@@ -621,7 +621,9 @@ private class EngineMerger implements Runnable {
                     } catch (EngineClosedException e) {
                         // we are being closed, ignore
                     } catch (OptimizeFailedEngineException e) {
-                        if (e.getCause() instanceof InterruptedException) {
+                        if (e.getCause() instanceof EngineClosedException) {
+                            // ignore, we are being shutdown
+                        } else if (e.getCause() instanceof InterruptedException) {
                             // ignore, we are being shutdown
                         } else if (e.getCause() instanceof ClosedByInterruptException) {
                             // ignore, we are being shutdown