Remove outer join based solely on join predicates

We currently remove outer joins based upon where clause predicates, but won't necessarily detect when to remove the the outer join based solely on join predicates:

SELECT * from pm1.g1 inner join (pm1.g2 left outer join pm1.g3 on pm1.g2.e1=pm1.g3.e1) on pm1.g1.e1=pm1.g3.e1