BUG #7556: "select not in sub query" plan very poor vs "not exists"

The following bug has been logged on the website:

Bug reference: 7556
Logged by: lt
Email address: l1t(at)tom(dot)com
PostgreSQL version: 9.2.0
Operating system: windows xp
Description:

test=# create table sli_test (id int primary key,info varchar(20));
test=# insert into sli_test select
generate_series(1,1000000),'digoal'||generate_series(1,1000000);
test=# analyze verbose sli_test;
test=# create table sli_test2 (id int not null,info varchar(20));
test=# insert into sli_test2 select
generate_series(1,1000000),'dbase'||generate_series(1,1000000);
test=# analyze verbose sli_test2;
test=# explain select max(a.info)from sli_test a where a.id not in(select
b.id from sli_test2 b where b.id<50000);
QUERY PLAN
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Aggregate (cost=9241443774.00..9241443774.01 rows=1 width=12)