BUG #12432: date_trunc returning wrong year and day

The following bug has been logged on the website:

Bug reference:      12432
Logged by:          Brian Quirion
Email address:      bquirion@gmail.com
PostgreSQL version: Unsupported/Unknown
Operating system:   Linux
Description:

foodb=> select date_trunc('week', now() - interval '1 week');
       date_trunc
------------------------
 2013-12-30 00:00:00-08
(1 row)

foodb=> select date_trunc('week', now() - interval '2 week');
       date_trunc
------------------------
 2014-12-22 00:00:00-08
(1 row)

I'mn using postgres 8.0.3