BUG #13940: rollback prepared is not working

The following bug has been logged on the website:

Bug reference: 13940
Logged by: Prathamesh Sonavane
Email address: prathameshsonavane(at)gmail(dot)com
PostgreSQL version: 9.2.14
Operating system: windows 7 enterprise
Description:

I am trying following prepared transaction:

(
BEGIN TRANSACTION;
PREPARE TRANSACTION 'B';
UPDATE xyz
SET jkl=20 WHERE lmn="XX";
)

Now it will change value of jkl to 20.
Now i am executing following query b4 "commit prepared B":

(
rollback PREPARED 'B';
)

indeed..it shud set jkl to its old value.but, still its showing 20 after
issuing this command. its very annoying. :(