Bug #11775 Variable character_set_system does not exist (sometimes).

Description:
The system variable character_set_system shows up in 'show variables' (as it should), but is not currently settable (deliberately), but it's also not selectable. In both cases it gives a misleading error message, claiming that the variable is unknown.

How to repeat:
mysql> show variables like 'character%';
+--------------------------+--------------------------------------------+
| Variable_name            | Value                                      |
+--------------------------+--------------------------------------------+
| character_set_client     | latin1                                     |
| character_set_connection | latin1                                     |
| character_set_database   | latin1                                     |
| character_set_results    | latin1                                     |
| character_set_server     | latin1                                     |
| character_set_system     | utf8                                       |
| character_sets_dir       | /usr/local/mysql-5.0/share/mysql/charsets/ |
+--------------------------+--------------------------------------------+
7 rows in set (0.01 sec)

mysql> select @@character_set_server;
+------------------------+
| @@character_set_server |
+------------------------+
| latin1                 |
+------------------------+
1 row in set (0.00 sec)

mysql> set character_set_server = latin1;
Query OK, 0 rows affected (0.00 sec)

mysql> select @@character_set_system;
ERROR 1193 (HY000): Unknown system variable 'character_set_system'
mysql> set character_set_system = utf8;
ERROR 1193 (HY000): Unknown system variable 'character_set_system'
mysql> 

Suggested fix:
'select @@character_set_system' should work, and attempting to set it should result in a more accurate error message.

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/internals/29222

Ok to push.

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/internals/29416

Fixed in 5.0.13

Noted in 5.0.13 changelog.