Foreign keys breaks tables permissions

Hi,

If one does:

create table master (
id integer not null,
primary key (id)
);

create table detail (
id integer not null,
master_id integer not null,
primary key (id),
foreign key (master_id) references master (id)
);

insert into master (id) values (1);

grant select on master to a_user;
grant select, insert, update, delete on detail to a_user;

then if login as "a_user" and does:

insert into detail (id, master_id) values (1, 10);

this will result in: "ERROR: master: Permission denied".

This seems a bug to me ? Isn't it ?

Regards,
Raul Chirea.