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)
referencesmaster (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.