Fix IndexMissingException in get template request

Fixes #2873

src/main/java/org/elasticsearch/action/admin/cluster/state/ClusterStateRequest.java

@@ -32,6 +32,8 @@ import java.io.IOException;
  */
 public class ClusterStateRequest extends MasterNodeOperationRequest<ClusterStateRequest> {
 
+    public final static String NONE = "_na";
+
     private boolean filterRoutingTable = false;
 
     private boolean filterNodes = false;
@@ -104,6 +106,11 @@ public class ClusterStateRequest extends MasterNodeOperationRequest<ClusterState
         return filteredIndices;
     }
 
+    public ClusterStateRequest filterOutIndices() {
+        this.filteredIndices = new String[]{NONE};
+        return this;
+    }
+
     public ClusterStateRequest filteredIndices(String... filteredIndices) {
         this.filteredIndices = filteredIndices;
         return this;

src/main/java/org/elasticsearch/action/admin/cluster/state/TransportClusterStateAction.java

@@ -95,6 +95,7 @@ public class TransportClusterStateAction extends TransportMasterNodeOperationAct
             }
 
             if (request.filteredIndices().length > 0) {
+                if (!(request.filteredIndices().length == 1 && ClusterStateRequest.NONE.equals(request.filteredIndices()[0]))) {
                     String[] indices = currentState.metaData().concreteIndicesIgnoreMissing(request.filteredIndices());
                     for (String filteredIndex : indices) {
                         IndexMetaData indexMetaData = currentState.metaData().index(filteredIndex);
@@ -103,6 +104,7 @@ public class TransportClusterStateAction extends TransportMasterNodeOperationAct
                         }
                     }
                 }
+            }
 
             if (request.filteredIndexTemplates().length > 0) {
                 for (String templateName : request.filteredIndexTemplates()) {

src/main/java/org/elasticsearch/rest/action/admin/indices/template/get/RestGetIndexTemplateAction.java

@@ -64,7 +64,7 @@ public class RestGetIndexTemplateAction extends BaseRestHandler {
                 .filterRoutingTable(true)
                 .filterNodes(true)
                 .filteredIndexTemplates(request.param("name"))
-                .filteredIndices("_na");
+                .filterOutIndices();
 
         clusterStateRequest.listenerThreaded(false);