fix build for single op

ge/hybrid/model/hybrid_model_builder.cc

@@ -141,6 +141,7 @@ Status CollectDependenciesForFusedGraph(NodeItem &node_item, std::set<OpDesc *>
 HybridModelBuilder::HybridModelBuilder(HybridModel &hybrid_model)
     : hybrid_model_(hybrid_model), runtime_param_(hybrid_model.root_runtime_param_) {
   ge_root_model_ = hybrid_model_.ge_root_model_;
+  hybrid_model_.root_graph_ = ge_root_model_->GetRootGraph();
 }
 
 Status HybridModelBuilder::Build() {
@@ -852,6 +853,7 @@ Status HybridModelBuilder::LoadGraph() {
            root_graph->GetAllNodesSize());
   }
 
+  hybrid_model_.root_graph_ = root_graph;
   GE_CHK_STATUS_RET(RelinkNextIteration(), "[%s] Relink NextIteration failed", GetGraphName());
   // Reset node id by topological order across all subgraphs
   int64_t index = 0;