BUG #1688: inheritance and foreign key creation problem

The following bug has been logged online:

Bug reference:      1688
Logged by:
Email address:      wrobell@pld-linux.org
PostgreSQL version: 8.0.3
Operating system:   Linux
Description:        inheritance and foreign key creation problem
Details:

-----------
create table employee (
    __key__      integer,
    name         varchar(10) not null,
    surname      varchar(20) not null,
    phone        varchar(12) not null,
    unique (name, surname),
    primary key (__key__)
);

create table boss (
    dep_fkey     integer unique
) inherits(employee);


create table department (
    __key__        integer,
    boss_fkey  integer unique,
    primary key (__key__),
    foreign key (boss_fkey) references boss(__key__) initially deferred
);

-----------

We can see that boss relation has __key__ column (inherited from employee
relation), but when executing above script PostgreSQL fails with message:

psql:script.sql:20: ERROR:  there is no unique constraint matching given
keys for referenced table "boss"