BUG #5458: Permission check is skipped by inheritance

The following bug has been logged online:

Bug reference: 5458
Logged by: Takahiro Itagaki
Email address: itagaki.takahiro@oss.ntt.co.jp
PostgreSQL version: 9.0beta1
Operating system: Linux (maybe ALL)
Description: Permission check is skipped by inheritance
Details:

Even if a non-superuser who has no permissions on
a parent and a child tables, he can retrieve data
from the parent when the two tables have inheritance
relationship.

The behavior seems to be changed in 9.0.
8.4 returns "permission denied" errors expectedly.

=== test case ===
- 'postgres' is a superuser.
- 'normal' is a non-superuser.

(9.0beta1)
=# CREATE TABLE parent (i integer);
=# CREATE TABLE child (i integer);
=# REVOKE ALL ON parent, child FROM public;
=# SET ROLE normal;
=> SELECT * FROM parent;
ERROR: permission denied for relation parent
=> SELECT * FROM child;
ERROR: permission denied for relation child
=> SET ROLE postgres;
=# ALTER TABLE child INHERIT parent;
=# SET ROLE normal;
=> SELECT * FROM parent; -- ???
i
---
(0 rows)

postgres=> SELECT * FROM child;
ERROR: permission denied for relation child

(8.4.3)
...
=# ALTER TABLE child INHERIT parent;
=# SET ROLE normal;
=> SELECT * FROM parent;
ERROR: permission denied for relation parent
=> SELECT * FROM child;
ERROR: permission denied for relation child