Bug #15316 SET value having comma not correctly handled

Description:
MySQL truncates a SET value, which is valid, doing INSERT

How to repeat:
create table set_test(a set("a,b","c,d") not null);
insert into set_test values("c,d");

Query OK, 1 row affected, 1 warning (0.01 sec)

mysql> show warnings;
+---------+------+----------------------------------------+
| Level   | Code | Message                                |
+---------+------+----------------------------------------+
| Warning | 1265 | Data truncated for column 'a' at row 1 |
+---------+------+----------------------------------------+
1 row in set (0.00 sec)

mysql> select * from set_test;
+---+
| a |
+---+
|   |
+---+
1 row in set (0.00 sec)

I was able to reproduce this bug with a recent clone of 5.1

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/1131

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/1261

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/4280

Fixed in 4.1.19

Noted in 4.1.19 changelog.

<literal>SET</literal> value definitions containing commas
were not rejected. Now a definition such as
<literal>SET('a,b','c,d')</literal> results in an error. (Bug
#15316)

It works for me in version 4.1.18-nt-max, but NOT in 4.1.19-community-max-nt. Is this expected behaviour? I.e. are commas no longer allowed in SET values?