Bug #6878 Crash with engine=memory

Description:
With engine=memory (only), some time after deleting two rows with NULLs, an INSERT 
statement crashes the server. 
 

How to repeat:
mysql> create table fh (s1 char(2)) engine=memory; 
Query OK, 0 rows affected (0.67 sec) 
 
mysql> insert into fh values ('b6'),(NULL),(NULL); 
Query OK, 3 rows affected (0.00 sec) 
Records: 3  Duplicates: 0  Warnings: 0 
 
mysql> delete from fh where s1 is null; 
Query OK, 2 rows affected (0.00 sec) 
 
mysql> insert into fh values ('b6'); 
Query OK, 1 row affected (0.00 sec) 
 
mysql> insert into fh values (''); 
ERROR 2013 (HY000): Lost connection to MySQL server during query

Thank you for the bug report I was able to repeat on latest Bk source server.

drop table if exists fh;
create table fh (s1 char(2)) engine=memory; 
insert into fh values (NULL), (NULL);
delete from fh where s1 is null;
insert into fh values (''), ('');

The bug appears only in case of char(*2*) field type.

Thank you for your bug report. This issue has been committed to our
source repository of that product and will be incorporated into the
next release.

If necessary, you can access the source repository and build the latest
available version, including the bugfix, yourself. More information 
about accessing the source trees is available at
    http://www.mysql.com/doc/en/Installing_source_tree.html

Additional info:

fixed in 4.0.23 and 4.1.8