BUG #8719: user creation including role does not work nor complain if in keyword is not specified

The following bug has been logged on the website:

Bug reference: 8719
Logged by: Andres More
Email address: andres(dot)more(at)intel(dot)com
PostgreSQL version: 9.3.1
Operating system: Amazon RDS
Description:

If I create a new user with an specific role it it not included unless IN is
included. However without IN the statement does not throw an error.

Amazon RDS postgres engine does not offer an admin user, but a light version
called rds_superuser.

CREATE USER sql_ro_user2 WITH ENCRYPTED PASSWORD 'sql_ro_password' ROLE
rds_superuser LOGIN

opscode_chef=> \du
List of roles
Role name | Attributes |
Member of
-----------------+------------------------------------------------+---------------------------------------------------------
opscode_chef | | {}
opscode_chef_ro | | {}
opscodepgsql | Create role, Create DB |
{rds_superuser}
rds_superuser | Cannot login |
{opscode_chef,opscode_chef_ro,sql_ro_user,sql_ro_user2}
rdsadmin | Superuser, Create role, Create DB, Replication | {}
sql_ro_user | | {}
sql_ro_user2 | | {}

CREATE USER sql_ro_user3 WITH ENCRYPTED PASSWORD 'sql_ro_password' IN ROLE
rds_superuser LOGIN

opscode_chef=> \du
List of roles
Role name | Attributes |
Member of
-----------------+------------------------------------------------+---------------------------------------------------------
opscode_chef | | {}
opscode_chef_ro | | {}
opscodepgsql | Create role, Create DB |
{rds_superuser}
rds_superuser | Cannot login |
{opscode_chef,opscode_chef_ro,sql_ro_user,sql_ro_user2}
rdsadmin | Superuser, Create role, Create DB, Replication | {}
sql_ro_user | | {}
sql_ro_user2 | | {}
sql_ro_user3 | |
{rds_superuser}