BUG #4669: pg_dump reports error about multiple rows

The following bug has been logged online:

Bug reference: 4669
Logged by: Vitaly Lopatin
Email address: vitaly(dot)lopatin(at)gmail(dot)com
PostgreSQL version: 8.3.6
Operating system: Red Hat Enterprise Linux 5.2
Description: pg_dump reports error about multiple rows
Details:

1. In start I used 8.3.1. Once, I got error:
ERROR: database is not accepting commands to avoid wraparound data loss in
database "ppcs_ts"
HINT: Stop the postmaster and use a standalone backend to vacuum database
"ppcs_ts".

2. I'd stopped postgresql and upgrade to 8.3.6

3. I've started postgres in stanalone mode and run 'vacuum full'.

4. I've started postgres in standart mode without any errors.

5. I've run pg_dump and I've got:
pg_dump: SQL command failed
pg_dump: Error message from server: ERROR: more than one row returned by a
subquery used as an expression
pg_dump: The command was: SELECT tableoid, oid, typname, typnamespace,
(SELECT rolname FROM pg_catalog.pg_roles WHERE oid = typowner) as rolname,
typinput
::oid as typinput, typoutput::oid as typoutput, typelem, typrelid, CASE WHEN
typrelid = 0 THEN ' '::"char" ELSE (SELECT relkind FROM pg_class WHERE oid
=
typrelid) END as typrelkind, typtype, typisdefined, typname[0] = '_' AND
typelem != 0 AND (SELECT typarray FROM pg_type te WHERE oid =
pg_type.typelem) =
oid AS isarray FROM pg_type

6. I run this query
ppcs_ts=# select oid,count(*) from pg_class group by oid having count(*) >
1;
oid | count
-------+-------
23744 | 2
(1 row)

and this query

ppcs_ts=# select ctid,xmin,xmax,cmin,cmax,oid,* from pg_class where
oid=23744;
ctid | xmin | xmax | cmin | cmax | oid |
relname | relnamespace | reltype | relowner | relam | relfilenode |
reltablespace | relpages | reltuples | reltoastrelid | reltoastidxid |
relhasindex | relisshared | relkind | relnatts | relchecks | reltriggers |
relukeys | relfkeys | relrefs | relhasoids | relhaspkey | relhasrules |
relhassubclass | relfrozenxid | relacl | reloptions
----------+------------+------+------------+------------+-------+-----------
--------------+--------------+---------+----------+-------+-------------+---
------------+----------+-----------+---------------+---------------+--------
-----+-------------+---------+----------+-----------+-------------+---------
-+----------+---------+------------+------------+-------------+-------------
---+--------------+--------+------------
(253,51) | 1713217376 | 0 | 6 | 6 | 23744 |
ppcsc_ip_clicks_analyze | 16394 | 23746 | 16391 | 0 |
121017126 | 0 | 1 | 2 | 0 |
0 | t | f | r | 2 | 0 |
1 | 0 | 0 | 0 | f | t | f |
f | 1713217349 | |
(237,3) | 1650691925 | 0 | 1672983373 | 1672983373 | 23744 |
ppcsc_ip_clicks_analyze | 16394 | 23746 | 16391 | 0 |
119761918 | 0 | 1 | 1 | 0 |
0 | t | f | r | 2 | 0 |
1 | 0 | 0 | 0 | f | t | f |
f | 1650691905 | |
(2 rows)

How I can to fix this problem?