BUG #2006: queryoptimizer and comparing a primary key of biginteger and a literal

The following bug has been logged online:

Bug reference: 2006
Logged by: Atanas Hristov
Email address: atanashristov(at)hotmail(dot)com
PostgreSQL version: 8.1 Beta 3
Operating system: FreeBSD 5
Description: queryoptimizer and comparing a primary key of biginteger
and a literal
Details:

foo=# CREATE TABLE foo (id BIGINT, CONSTRAINT foo_pk PRIMARY KEY(id) );

foo=# EXPLAIN ANALYZE SELECT 'foo' FROM foo WHERE id = CAST(0 AS BIGINT);
QUERY PLAN
----------------------------------------------------------------------------
--------------------------------
Index Scan using foo_pk on foo (cost=0.00..4.82 rows=2 width=0) (actual
time=0.113..0.113 rows=0 loops=1)
Index Cond: (id = 0::bigint)

foo=# EXPLAIN ANALYZE SELECT 'foo' FROM foo WHERE id = 0; -- WHY POSTGRES
DOES NOT IMPLICITLY DO CASTING OF THE LITERAL "0" ??????
QUERY PLAN
----------------------------------------------------------------------------
------------------
Seq Scan on foo (cost=0.00..22.50 rows=2 width=0) (actual
time=0.003..0.003 rows=0 loops=1)
Filter: (id = 0)