bad message or bad privilege check in foreign key constraint

apparently revoking update rights on referencing table blocks deletes on master table:

(user test, database test, user test is not superuser)

> create table a (id serial primary key, x text);
NOTICE:  CREATE TABLE will create implicit sequence "a_id_seq" for serial column "a.id"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "a_pkey" for table "a"
CREATE TABLE

> create table b (id serial primary key, a_id int4 references a(id) );
NOTICE:  CREATE TABLE will create implicit sequence "b_id_seq" for serial column "b.id"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "b_pkey" for table "b"
CREATE TABLE

> insert into a (id) values (1);
INSERT 0 1

> insert into b (a_id) values (1);
INSERT 0 1

> revoke update on b from test;
REVOKE

> delete from a where id = 1;
ERROR:  permission denied for relation b
CONTEXT:  SQL statement "SELECT 1 FROM ONLY "public"."b" x WHERE $1 OPERATOR(pg_catalog.=) "a_id" FOR SHARE OF x"

now, i know that the sql shown in context comes from foreign key trigger, but is definitely not obvious for everybody,
somaybe the message should be cleared 
a bit in this case.

on the other hand - i'm not really sure that update rights should be neccessary in such case.

best regards,

depesz

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