BUG #5418: psql exits after using tab-completion with error message

The following bug has been logged online:

Bug reference: 5418
Logged by: Ben Madin
Email address: ben(at)ausvet(dot)com(dot)au
PostgreSQL version: 8.4.3
Operating system: Mac OS X 10.6.3
Description: psql exits after using tab-completion with error message
Details:

G'day,

this problem appear to be intermittent - in so far as I don't always notice
it. It has been happening for a number of versions (since 8.3 at least) and
it might work or it might not, but I can't really pick what has changed when
it starts happening. Once it starts, it seems very hard to stop. Very
anecdotally, I think it only happens when the characters entered so far are
ambiguous (ie could be more than one table) and the tables are recently
added to the database.

Here is an example : (I wanted the abattoir table, so I had typed \d aba and
then pressed the tab key)

psql (8.4.3)
Type "help" for help.

prices=# SELECT version();
version

----------------------------------------------------------------------------
--------------------------------------------------------------------
PostgreSQL 8.4.3 on i386-apple-darwin10.3.0, compiled by GCC
i686-apple-darwin10-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5646) (dot 1),
64-bit
(1 row)

prices=# \set VERBOSITY verbose
prices=# \d abapsql(11407) malloc: *** error for object 0xe: pointer being
freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap

but if I had only typed \d a, it would have just waited (as there are two
other tables starting with a)

I have tried :
1. restarting the terminal
2. restarting the pg_server
3. rebooting the system
4. a few cycles of upgrades
5. dropping and reloading the database itself.

and I don't know where else to go. I have no idea about what
malloc_error_break means or where to start.

I hope this is helpful enough, please let me know if you require further
information.

cheers

Ben