pg_dump 8.0.3 failing against PostgreSQL 7.3.2

I am experiencing a problem with dumping one specific database on
a cluster. All 143 other databases dump without giving errors.

The server runs PostgreSQL 7.3.2 on OpenBSD (I know :). pg_dump
is version 8.0.3 on Windows (upgraded from 8.0.1 which had the
same problem). The error message is:

pg_dump: SQL command failed
pg_dump: Error message from server: ERROR: Cannot cast type
"unknown" to text
pg_dump: The command was: SELECT proretset, prosrc, probin,
null::text as proargnames, provolatile, proisstrict, prosecdef,
(SELECT lanname FROM pg_catalog.pg_language WHERE oid = prolang)
as lanname FROM pg_catalog.pg_proc WHERE oid =
'8331054'::pg_catalog.oid

Below I have copy pasted the console log which has some
additional information. This bug, or a related one, seems to have
been registered previously as bug #1455
http://archives.postgresql.org/pgsql-bugs/2005-02/msg00021.php

Jochem

> C:\Program Files\PostgreSQL\8.0\bin>psql --version
> psql (PostgreSQL) 8.0.3
>
> C:\Program Files\PostgreSQL\8.0\bin>pg_dump wedstrijdzeilen > "z:\backup\databases\2005-06-06\wedstrijdzeilen.sql"
> Password:
> pg_dump: SQL command failed
> pg_dump: Error message from server: ERROR: Cannot cast type "unknown" to text
> pg_dump: The command was: SELECT proretset, prosrc, probin, null::text as proargnames, provolatile, proisstrict, prosecd
> ef, (SELECT lanname FROM pg_catalog.pg_language WHERE oid = prolang) as lanname FROM pg_catalog.pg_proc WHERE oid = '833
> 1054'::pg_catalog.oid
>
> C:\Program Files\PostgreSQL\8.0\bin>psql wedstrijdzeilen
> Password:
> Welcome to psql 8.0.3, the PostgreSQL interactive terminal.
>
> Type: \copyright for distribution terms
> \h for help with SQL commands
> \? for help with psql commands
> \g or terminate with semicolon to execute query
> \q to quit
>
> Warning: Console code page (437) differs from Windows code page (1252)
> 8-bit characters may not work correctly. See psql reference
> page "Notes for Windows users" for details.
>
> oli=> select version();
> version
> ---------------------------------------------------------------------
> PostgreSQL 7.3.2 on i386-unknown-openbsd3.2, compiled by GCC 2.95.3
> (1 row)
>
> wedstrijdzeilen=> SELECT proretset, prosrc, probin, null::text as proargnames, provolatile, proisstrict, prosecdef, (SEL
> ECT lanname FROM pg_catalog.pg_language WHERE oid = prolang) as lanname FROM pg_catalog.pg_proc WHERE oid = '8331054'::p
> g_catalog.oid;
> proretset |
>
> prosrc
>
> | probin | proargnames | provolatile | proisstrict
> | prosecdef | lanname
> -----------+------------------------------------------------------------------------------------------------------------
> ------------------------------------------------------------------------------------------------------------------------
> ------------------------------------------------------------------------------------------------------------------------
> ------------------------------------------------------------------------------------------------------------------------
> ----------------------------------------------------------------------+--------+-------------+-------------+------------
> -+-----------+---------
> t |
> SELECT j.parent_id as id,
> (SELECT singular FROM dswz.translations WHERE id = t.name AND language_id = (SELECT dswz.check_creator_i
> d ($1, $2, $3, $4))),
> street,
> house_number,
> zipcode,
> city,
> (SELECT singular FROM dswz.translations WHERE id = nations.name AND language_id = (SELECT dswz.check_cre
> ator_id ($1, $2, $3, $4)))
> FROM dswz.view_addresses a LEFT JOIN dswz.nations ON country = nations.id,
> dswz.joins($1, $2,$3,$4) j,
> dswz.object_types t
> WHERE j.child_id = a.id
> AND t.id = a.type
> AND j.cancel_time > now();
> | - | | v | f | t | sql
> (1 row)