BUG #1733: Function visibility in transactions error

The following bug has been logged online:

Bug reference: 1733
Logged by: Robert Grabowski
Email address: grabba(at)env(dot)pl
PostgreSQL version: 8.0.1
Operating system: Linux 2.6.12-gentoo
Description: Function visibility in transactions error
Details:

I have problem with function visibility in transaction when I do create and
drop function. There is an example.

I have two sessions:

1: CREATE FUNCTION test () RETURNS integer AS 'select 1' LANGUAGE 'sql';
CREATE FUNCTION

1: SELECT test();
test
------
1
(1 row)

2: BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
BEGIN

2: SELECT test();
test
------
1
(1 row)

1: DROP FUNCTION test ();
DROP FUNCTION

1: CREATE FUNCTION test () RETURNS integer AS 'select 2' LANGUAGE 'sql';
CREATE FUNCTION

1: SELECT test();
test
------
2
(1 row)

2: SELECT test();
test
------
1
(1 row)

It's ok. In transaction I have old definition of test function.

2: SELECT test();
test
------
2
(1 row)

!!!! Strange! Second call of the same function gets other result.

In READ COMMITED transactions I have the same results.