reduce() of empty sequence with no initial value

[Daniel Holbach]

  File "/var/lib/python-support/python2.5/django/core/handlers/base.py", line 86, in get_response
    response = callback(request, *callback_args, **callback_kwargs)

  File "/srv/loco.ubuntu.com/loco_directory/venues/views.py", line 34, in venue_list
    'countries_without_continent_have_venues': countries_without_continent_have_venues(),

  File "/srv/loco.ubuntu.com/loco_directory/teams/models.py", line 61, in countries_without_continent_have_venues
    return len(flat_list(list_of_venues))>0

  File "/srv/loco.ubuntu.com/loco_directory/common/utils.py", line 10, in flat_list
    return reduce(lambda a,b: a.extend(b) or a, some_list)

[Daniel Holbach (dholbach)]

Attached branch was already cowboyed into production.