9.6beta subplan target list bug

Found a bug:

create table foo as select x, floor(random()*100)::int as y,
floor(random()*100)::int as z from generate_series(1,1000000) f(x);

explain select count(y) filter (where y<0.01) from foo where x < 10000;

ERROR:  variable not found in subplan target list
STATEMENT:  select count(y) filter (where y<0.01) from foo where x < 10000;

Bisects to:

commit 59a3795c2589a0e6dfe4d9a886de9423b3f8b057
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Sun Jun 26 12:08:12 2016 -0400
   Simplify planner's final setup of Aggrefs for partial aggregation.

Cheers,

Jeff