Enable External Job fails with role rights

In Oracle 10g R2 their would appear to be a bug when enabling a job via a user owned procedure like this:
BEGIN
MYUSER.PKG_JOBS.ENABLE_JOBS;
END;
which my activate a whole bunch of jobs in a schedule.

Say the MYUSER has been granted MYROLE which is defined as:
grant create job,
execute any program,
execute any class,
create external job,
manage scheduler TO MYROLE;

In Order for the procedure call above to execute a:
DBMS_SCHEDULER.ENABLE ( 'MYJOB' );
which uses an EXECUTABLE (external) shell or program to run you must grant the 'create external job' directly to MYUSER.

Interestingly if MYUSER enables the job by calling DBMS_SCHEDULER.ENABLE directly it works fine but not if the enable is stored in a package which belongs to MYUSER.

This useful "GUIDE TO RUNNING EXTERNAL JOBS ON 10g WITH DBMS_SCHEDULER" may help in understanding what issues are involved with calling external jobs under Oracle.