No handling for session expire

[Radomir Dopieralski]

When the login session expires, and I try to perform any operation, for example create a resource class, I get the generic "Error: An error occurred. Please try again later." and this traceback in the logs:

Traceback:
File "/home/sheep/devel/horizon/.venv/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  187. response = middleware_method(request, response)
File "/home/sheep/devel/horizon/horizon/middleware.py" in process_response
  117. queued_msgs = request.horizon['async_messages']

Exception Type: AttributeError at /infrastructure/resource_classes/create/
Exception Value: 'WSGIRequest' object has no attribute 'horizon'

It could be better to have me redirected to the login page instead.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/53113

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/53113
Committed: http://github.com/openstack/horizon/commit/7d72e5f3a40379285dd4b95f24934699c6ca4a21
Submitter: Jenkins
Branch: master

commit 7d72e5f3a40379285dd4b95f24934699c6ca4a21
Author: Radomir Dopieralski <email address hidden>
Date: Tue Oct 22 15:11:18 2013 +0200

    Fix AttributeError on Ajax calls with expired session

    When the session expires and horizon does an Ajax call (for example,
    to get a modal window), an exception is raised instead of redirecting
    to the login screen, because the exception handler in the horizon
    middleware doesn't add the "horizon" attribute to the request. This is
    a very simple fix to avoid throwing the exception.

    Change-Id: I663999dd616b1a4fa3292615eecf3cc44c3e808a
    Closes-bug: #1224458