Comment 1 for bug 266309

The following patch worked for me:

+++ Mailman/Cgi/admin.py 2009-09-30 12:06:16.000000000 +0200
@@ -107,6 +107,8 @@ def main():
     # Is this a log-out request?
     if category == 'logout':
         print mlist.ZapCookie(mm_cfg.AuthListAdmin)
+ if mm_cfg.ALLOW_SITE_ADMIN_COOKIES:
+ print mlist.ZapCookie(mm_cfg.AuthSiteAdmin)
         Auth.loginpage(mlist, 'admin', frontpage=1)
         return

It removes the (global) site-admin cookie if the "logout" button is clicked in the admin interface of any list.
Gero