message: Explicitly specify the value of all the attributes for the newly created Assign
  nodes since we can't always rely on TF calling AddDefaultAttrsToGraphDef.
diff: @@ -641,6 +641,8 @@ bool SchedulingPass(Cluster* cluster, GrapplerItem* item) {
  initialize->set_op("Assign");
  initialize->set_device(device);
  (*initialize->mutable_attr())["T"].set_type(dtype);
  + (*initialize->mutable_attr())["use_locking"].set_b(false);
  + (*initialize->mutable_attr())["validate_shape"].set_b(false);
  *initialize->add_input() = tmp_var->name();
  *initialize->add_input() = zeros->name();
  