sitemap.xml and 'unknown timezone'

[shacker]

Django sitemaps worked fine on a previous server, and work fine in my development environment, but break in production on a new server, with:

ValidationError: [u'Unknown timezone']

(traceback below)

The docs don't mention anything about timezone configuration or dependencies:

https://docs.djangoproject.com/en/dev/ref/contrib/sitemaps/

The server's timezone is correctly set  to America/Los_Angeles. I'm not sure what else to look at here and Google's turning up nothing. 

Got a clue? Thanks.

Django 1.3

RHEL 5.7

./s

Traceback (most recent call last):

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/core/handlers/base.py", line 111, in get_response

   response = callback(request, *callback_args, **callback_kwargs)

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/contrib/sitemaps/views.py", line 39, in sitemap

   urls.extend(site().get_urls(page=page, site=current_site))

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/contrib/sitemaps/__init__.py", line 75, in get_urls

   for item in self.paginator.page(page).object_list:

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/db/models/query.py", line 107, in _result_iter

   self._fill_cache()

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/db/models/query.py", line 772, in _fill_cache

   self._result_cache.append(self._iter.next())

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/db/models/query.py", line 286, in iterator

   obj = model(*row[index_start:aggregate_start])

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/db/models/base.py", line 297, in __init__

   setattr(self, field.attname, val)

 File "/home/username/virtualenvs/kdmc/lib/python2.7/site-packages/django/db/models/fields/subclassing.py", line 99, in __set__

   obj.__dict__[self.field.name] = self.field.to_python(value)

 File "build/bdist.linux-x86_64/egg/timezones/fields.py", line 43, in to_python

   return coerce_timezone_value(value)

 File "build/bdist.linux-x86_64/egg/timezones/utils.py", line 34, in coerce_timezone_value

   raise ValidationError("Unknown timezone")

ValidationError: [u'Unknown timezone']