BUG #2507: Problem using two-phase commit

The following bug has been logged online:

Bug reference:      2507
Logged by:          N. Ramirez
Email address:      noramirez@speedy.com.ar
PostgreSQL version: 8.1.4
Operating system:   Linux Suse 9
Description:        Problem using two-phase commit
Details:

I do not have an operation as it must be when use the functions to do
2-phase commit

Example create table prueba (a int, b int);
begin;
PREPARE TRANSACTION 'aaaa';
insert into prueba values (1,2);
ROLLBACK PREPARED 'aaaa';  select * from prueba
a               b
-----------------------------
1               2
because?
it did not do rollback?
as it is used the method of 2-phase commit?
idem for use of dblink