Reverted r17577 because it's actually possible to use a time zone that isn't...

Reverted r17577 because it's actually possible to use a time zone that isn't the system time zone without pytz, thanks to the TZ environment variable.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@17578 bcc190cf-cafb-0310-a4f2-bffc1f526a37