Drop user problem and DENY command

Hi All,

Two weeks ago somebody had reported that drop user don't remove rights from
relacl field of pg_class. This problem is more serious if you delete a group
from pg_group without remoking rigths before. It causes backend terminates
abnormally.

Maybe interesting for others!! Could anybody include DENY sql command in
TODO list.

My problem is: A group have rigths to access some table. I include a new
user in this group, but for three months he will not have rights to access
this table. So, if the new user have no rigths, he will get rights from his
group. I think it would be enough DENY command (deny all on sometable from
newuser) includes something like "NEWUSER=" in relacl field.

Just more one question: Aclitem type have the following rigths: =arwR
(insert, select, update/delete, create rule, I suppose).
How could I grant update and revoke delete permissions on a table ?

Best Regards,

Ricardo Coelho.

P.S. I'm using Pgsql 6.5 Linux Intel