Please explain the following sequence of events. Specifically, why did revoking create privileges on a table space from mjacobson create an explicit access privilege listing for postgres, and then re-granting the same privilege created another explicit rule for mjacobson? What have I done and how can I reverse this?


Code:
postgres@zeus=>[local]:ises=# \db+
                        List of tablespaces
    Name    |  Owner   | Location | Access privileges | Description
------------+----------+----------+-------------------+-------------
 pg_default | postgres |          |                   |
 pg_global  | postgres |          |                   |
(2 rows)

postgres@zeus=>[local]:ises=# revoke create on tablespace pg_default from mjacobson;
REVOKE
postgres@zeus=>[local]:ises=# \db+
                         List of tablespaces
    Name    |  Owner   | Location |  Access privileges  | Description
------------+----------+----------+---------------------+-------------
 g_default | postgres |          | postgres=C/postgres |
 pg_global  | postgres |          |                     |
(2 rows)

postgres@zeus=>[local]:ises=# grant create on tablespace pg_default to mjacobson;
GRANT
postgres@zeus=>[local]:ises=# \db+
                          List of tablespaces
    Name    |  Owner   | Location |  Access privileges   | Description
------------+----------+----------+----------------------+-------------
 pg_default | postgres |          | postgres=C/postgres +|
            |          |          | mjacobson=C/postgres |
 pg_global  | postgres |          |                      |
(2 rows)