Why does make_noname insert a SeqScan above sort/material node? - Mailing list pgsql-hackers

Does anyone know why make_noname (in createplan.c) insists on putting
a SeqScan plan node above the Sort or Material node it's generating?
As far as I can tell, it's a waste of cycles:

1. planner.c doesn't bother with a SeqScan above the Sorts it makes.
2. The executor's nodeSeqscan.c just redirects all its calls to the  outerPlan node, if it has an outerPlan.
3. Things seem to work fine without it ;-)

However, I'm not quite ready to commit this change without consultation.
Does anyone know what this was for?
        regards, tom lane