full join qualifications on 8.3.1 vs. 8.3.6

Given:

select * from test1 full join test2 using (a,b) where b=1;

8.3.1 and CVS HEAD produce a plan in which the b=1 condition is pushed
down into each side of the join, but 8.3.6 and 8.3.7 do not.

Is this intentional? I wasn't able to identify anything applicable in
the release notes.

testcase used:
create table test1 (a integer, b integer, c text);
create table test2 (a integer, b integer, c text);
insert into test1 select i,i,i::text from generate_series(1,10000) i;
insert into test2 select i,i,i::text from generate_series(1,10000) i;
create index test1_idx on test1 (b);
create index test2_idx on test2 (b);
explain select * from test1 full join test2 using (a,b) where b = 1;

-- 
Andrew (irc:RhodiumToad)