BUG #5516: Memory grows up problem

The following bug has been logged online:

Bug reference: 5516
Logged by: Yuhui
Email address: xingyuhui(at)gmail(dot)com
PostgreSQL version: 8.3,8.2,8.1
Operating system: Linux,Windows
Description: Memory grows up problem
Details:

Do the follow setp to reproduce the problem:
1,
CREATE TABLE mem_leak(A INT, B char(50) default 'abcdefg');
2,
INSERT INTO mem_leak(a) VALUES(generate_series(1,200000000));

The memory which the execution process occupation will grows larger and
larger until all the memory is gone or the process is over or the process is
killed by the os.
If in create table statementthe "B char(50)" is changed to "B varchar(50)"
or delete the "default 'abcdefg'" the memory will not grow anymore.

The problem is not happen in the 8.4 above version.