Confusion with Etc/GMT-8 time zone

[Amit <amit.uttam@gmail.com>]

Hello,

This on a debian wheezy/testing system:

Currently, my time zone is set to 'America/Los_Angeles':

 $ cat /etc/timezone
 America/Los_Angeles

 $ date
 Mon Jan 28 11:12:01 PST 2013

Changing it to 'Etc/GMT-8', which should be equivalent to Los Angeles's
time zone results in:

 $ echo "Etc/GMT-8" | sudo tee /etc/timezone
 Etc/GMT-8

 $ cat /etc/timezone
 Etc/GMT-8

 $ sudo dpkg-reconfigure --frontend noninteractive tzdata
 Current default time zone: 'Etc/GMT-8'
 Local time is now:      Tue Jan 29 03:14:57 GMT-8 2013.
 Universal Time is now:  Mon Jan 28 19:14:57 UTC 2013.

Notice that the day moved to Jan  29th. This doesn't seem to make any
sense. Is this a bug?

NOTE: Repeating the above steps for Etc/GMT+8 results in the correct and
expected time.

Thanks,
Amit