fix wrong check on close

Author: kimchy

src/main/java/org/elasticsearch/action/bulk/BulkProcessor.java

@@ -243,7 +243,6 @@ private void executeIfNeeded() {
         if (closed) {
             throw new ElasticSearchIllegalStateException("bulk process already closed");
         }
-        this.closed = true;
         if (!isOverTheLimit()) {
             return;
         }