Bug #4346 SUM() Function returns 0 instead of NULL in a case

Description:
The SUM() function should return NULL if the return set has no rows. I found a case where this does not work with 3.23.48.

Following Statement:
SELECT parent.parent_id, SUM( child.value ) AS result FROM child RIGHT JOIN parent ON child.id_parent = parent.parent_id GROUP BY parent.parent_id;

returns (FALSE !):
+-----------+--------------+
| parent_id | result |
+-----------+--------------+
|         1 |           90 |
|         2 |            0 |
|         3 |            0 |
+-----------+--------------+

But following Statement:
SELECT SUM(value) FROM child WHERE 1=2 ;

returns: 
+------------+
| SUM(value) |
+------------+
|       NULL |
+------------+

Version 4.0.13
returns in Case 1 (RIGHT !):

+-----------+--------------+
| parent_id | result |
+-----------+--------------+
|         1 |           90 |
|         2 |         NULL |
|         3 |         NULL |
+-----------+--------------+

How to repeat:
CREATE TABLE parent (
  parent_id int(11) NOT NULL auto_increment,
  PRIMARY KEY  (parent_id)
) TYPE=MyISAM AUTO_INCREMENT=4 ;

INSERT INTO parent VALUES (1);
INSERT INTO parent VALUES (2);
INSERT INTO parent VALUES (3);

CREATE TABLE child (
  child_id int(11) NOT NULL auto_increment,
  id_parent int(11) NOT NULL default '0',
  value int(11) NOT NULL default '0',
  PRIMARY KEY  (child_id)
) TYPE=MyISAM AUTO_INCREMENT=3 ;

INSERT INTO child VALUES (1, 1, 34);
INSERT INTO child VALUES (2, 1, 56);

SELECT parent.parent_id, SUM( child.value ) AS result FROM child RIGHT JOIN parent ON child.id_parent = parent.parent_id GROUP BY parent.arent_id;

Suggested fix:
SELECT parent.parent_id, IF( COUNT(child.value) = 0, 'NULL', SUM(child.value)) AS result FROM child RIGHT JOIN parent ON child.id_parent = parent.parent_id GROUP BY parent.parent_id;

returns (RIGHT !):
+-----------+--------+
| parent_id | result |
+-----------+--------+
|         1 | 90     |
|         2 | NULL   |
|         3 | NULL   |
+-----------+--------+

I can verify that this occurs even against the last 3.23 release (3.23.58), however 4.0 forward does return NULL, and 3.23 is receiving only very critical bug fixes now.