message: copy properties when copying lambda expression
diff: @@ -18,7 +18,6 @@ bool LambdaExpression::Equals(const LambdaExpression *a, const LambdaExpression
  }
  hash_t LambdaExpression::Hash() const {
  -
  hash_t result = lhs->Hash();
  ParsedExpression::Hash();
  result = CombineHash(result, expr->Hash());
  @@ -26,7 +25,9 @@ hash_t LambdaExpression::Hash() const {
  }
  unique_ptr<ParsedExpression> LambdaExpression::Copy() const {
  - return make_unique<LambdaExpression>(lhs->Copy(), expr->Copy());
  + auto copy = make_unique<LambdaExpression>(lhs->Copy(), expr->Copy());
  + copy->CopyProperties(*this);
  + return move(copy);
  }
  void LambdaExpression::Serialize(FieldWriter &writer) const {
  