BUG: Vacuum Analyze - datumGetSize: Invalid typLen 0

System: NetBSD / Alpha 1.6 (64 bit)
Postgresql 7.3.2

Bug: after vacuum analyze, I'm unable to do a simple select. Instead I'm
getting this error:
 ERROR:  datumGetSize: Invalid typLen 0

Many thanks to Teodor Sigaev for helping verify this bug. The following
test suite came from Teodor:

Reproduce bug:
initdb and start postmaster
%createdb foo
%psql foo < bug.sql
CREATE TABLE
INSERT 16996 1
INSERT 16997 1
CREATE TABLE
INSERT 17003 1 ts_name | ts_name
---------+--------- default | default default | default
(2 rows)

VACUUM
ERROR:  datumGetSize: Invalid typLen 0


bug.sql is very simple:
------------------------------------------------
CREATE TABLE pg_ts_cfgmap (    ts_name text
);

insert into pg_ts_cfgmap values ('default');
insert into pg_ts_cfgmap values ('default');


CREATE TABLE pg_ts_cfg (    ts_name text
);

insert into pg_ts_cfg values ('default');

select       *
from        pg_ts_cfgmap,        pg_ts_cfg
where        pg_ts_cfgmap.ts_name = pg_ts_cfg.ts_name;


vacuum analyze pg_ts_cfgmap;

select        *
from        pg_ts_cfgmap,        pg_ts_cfg
where        pg_ts_cfgmap.ts_name = pg_ts_cfg.ts_name;

---------------------------------------------------

Thomas