Strange behavior with inherited role permissions in information_schema

information_schema_role_inheritance.sql

-- With this schema in place..
-- https://github.com/postgraphql/postgraphql/blob/master/examples/forum/schema.sql
-- try running the following:

set role forum_example_postgraphql;
select distinct privilege_type from information_schema.role_table_grants where table_name = 'person';

-- privilege_type 
------------------
-- DELETE
-- SELECT
-- UPDATE
--(3 rows)

-- OK

set role postgres;
create role person_creator_parent noinherit;
create role person_creator noinherit;
grant person_creator_parent to forum_example_postgraphql;
grant person_creator to person_creator_parent;
grant insert on table forum_example.person TO person_creator;
set role forum_example_postgraphql;
select distinct privilege_type from information_schema.role_table_grants where table_name = 'person';

-- privilege_type 
------------------
-- DELETE
-- SELECT
-- UPDATE
--(3 rows)

-- OK

set role postgres;
alter role person_creator with inherit;
set role forum_example_postgraphql;
select distinct privilege_type from information_schema.role_table_grants where table_name = 'person';

-- privilege_type 
------------------
-- DELETE
-- SELECT
-- UPDATE
--(3 rows)

set role postgres;
alter role person_creator_parent with inherit;
set role forum_example_postgraphql;
select distinct privilege_type from information_schema.role_table_grants where table_name = 'person';

-- OK

-- privilege_type 
------------------
-- DELETE
-- SELECT
-- UPDATE
--(3 rows)

-- Hmmm, I expected to see INSERT here

set role person_creator_parent;
select distinct privilege_type from information_schema.table_privileges where table_name = 'person';

-- privilege_type 
------------------
-- INSERT
--(1 row)

-- OK

set role forum_example_postgraphql;
select distinct privilege_type from information_schema.role_table_grants where table_name = 'person';

-- privilege_type 
------------------
-- DELETE
-- INSERT
-- SELECT
-- UPDATE
--(4 rows)

-- Wait, now it works!?

-- Reset
set role postgres;
revoke all privileges on forum_example.person from person_creator;
revoke all privileges on forum_example.person from person_creator_parent;
drop role person_creator;
drop role person_creator_parent;