query syntax change?

This query works in 7.0.3...

SELECT p.*, e.id AS "employee_id", e.ref_name, 
       e.business_line_id, e.record_status_id AS "emp_record_status_id" 
FROM person p, employee e 
WHERE e.person_id = p.id 

UNION ALL 

SELECT p.*, NULL AS "employee_id", NULL AS "ref_name", 
       NULL AS "business_line_id", NULL AS "emp_record_status_id" 
FROM person p 
WHERE NOT EXISTS (SELECT id FROM employee WHERE person_id = p.id) 
ORDER BY p.sortable_last_name;

but in 7.1.2 it reports the following error:

	ERROR:  Relation 'p' does not exist

Anyone understand why?

Regards,
Ed Loehr