Added helpful error message to SiteManager.get_current() if the user hasn't set SITE_ID
Added helpful error message to SiteManager.get_current() if the user hasn't set SITE_ID

--HG--
extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%405652

adieu/django-nonrel,adieu/django-nonrel,adieu/django-nonrel