get_and_delete_messages is called in auth context processor for every request

[tangerine]

user.get_and_delete_messages() is called irrespective of whether the request is for a page within the admin interface or not. Although it's typically only one extraneous query, it is extra overhead which is unnecessary for the vast majority of requests. Maybe it could be moved out in to a admin context processor which simply adds messages to the context?

[James Bennett]

The messaging system is not an admin-specific feature; it is a general-purpose part of Django's authentication framework and is intended for use in any code which needs the ability to display such messages to a user (see, for example, its use in the views in django.views.generic.create_update).