message: small fix to travis build error
diff: @@ -42,7 +42,7 @@ unique_ptr<ExpressionState> ExpressionExecutor::InitializeState(BoundConjunction
  children.push_back(child.get());
  }
  result->AddIntermediates(children);
  - return result;
  + return move(result);
  }
  void ExpressionExecutor::Execute(BoundConjunctionExpression &expr, ExpressionState *state, Vector &result) {
  