Fixed #10793 -- Stopped caching paginator instances in sitemap classes to...

Fixed #10793 -- Stopped caching paginator instances in sitemap classes to prevent stale sitemaps. Thanks, gnosek, krzysiumed and adam_przybyla.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17468 bcc190cf-cafb-0310-a4f2-bffc1f526a37