Previous 'session time out' error message is not being clean - django

Question

I'm using Django 1.5.5, and I'm using the built-in authentication system provided by Django.
I define SESSION_TIMEOUT=600 in my settings.py, so after 10 minutes idle, user will be redirected to the login page with 'Session timed out' warning as request.COOKIES.logout_reason is displayed on the page.
The problem is, after user re-login again, and manually log out the system. The 'Session timed out' warning message is still displayed, I suppose that request.COOKIES.logout_reason variable should be cleaned up after successfully log in.
What could be the problem and where are the code I might need to look at? I'm inexperienced on Django and haven't found related discussion yet. Thanks.
Updated: the login and logout function I use in django.contrib.auth.views.py
from django.contrib.auth import REDIRECT_FIELD_NAME, login as auth_login, logout as auth_logout, get_user_model
from django.contrib.auth.decorators import login_required
from django.contrib.auth.forms import AuthenticationForm, PasswordResetForm, SetPasswordForm, PasswordChangeForm
from django.contrib.auth.tokens import default_token_generator
from django.contrib.sites.models import get_current_site
#sensitive_post_parameters()
#csrf_protect
#never_cache
def login(request, template_name='registration/login.html',
redirect_field_name=REDIRECT_FIELD_NAME,
authentication_form=AuthenticationForm,
current_app=None, extra_context=None):
"""
Displays the login form and handles the login action.
"""
redirect_to = request.REQUEST.get(redirect_field_name, '')
if request.method == "POST":
form = authentication_form(data=request.POST)
if form.is_valid():
# Ensure the user-originating redirection url is safe.
if not is_safe_url(url=redirect_to, host=request.get_host()):
redirect_to = resolve_url(settings.LOGIN_REDIRECT_URL)
# Okay, security check complete. Log the user in.
auth_login(request, form.get_user())
if request.session.test_cookie_worked():
request.session.delete_test_cookie()
return HttpResponseRedirect(redirect_to)
else:
form = authentication_form(request)
request.session.set_test_cookie()
current_site = get_current_site(request)
context = {
'form': form,
redirect_field_name: redirect_to,
'site': current_site,
'site_name': current_site.name,
}
if extra_context is not None:
context.update(extra_context)
return TemplateResponse(request, template_name, context,
current_app=current_app)
def logout(request, next_page=None,
template_name='registration/logged_out.html',
redirect_field_name=REDIRECT_FIELD_NAME,
current_app=None, extra_context=None):
"""
Logs out the user and displays 'You are logged out' message.
"""
auth_logout(request)
if redirect_field_name in request.REQUEST:
next_page = request.REQUEST[redirect_field_name]
# Security check -- don't allow redirection to a different host.
if not is_safe_url(url=next_page, host=request.get_host()):
next_page = request.path
if next_page:
# Redirect to this page until the session has been cleared.
return HttpResponseRedirect(next_page)
current_site = get_current_site(request)
context = {
'site': current_site,
'site_name': current_site.name,
'title': _('Logged out')
}
if extra_context is not None:
context.update(extra_context)
return TemplateResponse(request, template_name, context,
current_app=current_app)
and the auth_login() and auth_logout() will call to the following functions in django.contrib.auth.__init__.py:
def login(request, user):
"""
Persist a user id and a backend in the request. This way a user doesn't
have to reauthenticate on every request. Note that data set during
the anonymous session is retained when the user logs in.
"""
if user is None:
user = request.user
# TODO: It would be nice to support different login methods, like signed cookies.
if SESSION_KEY in request.session:
if request.session[SESSION_KEY] != user.pk:
# To avoid reusing another user's session, create a new, empty
# session if the existing session corresponds to a different
# authenticated user.
request.session.flush()
else:
request.session.cycle_key()
request.session[SESSION_KEY] = user.pk
request.session[BACKEND_SESSION_KEY] = user.backend
if hasattr(request, 'user'):
request.user = user
rotate_token(request)
user_logged_in.send(sender=user.__class__, request=request, user=user)
def logout(request):
"""
Removes the authenticated user's ID from the request and flushes their
session data.
"""
# Dispatch the signal before the user is logged out so the receivers have a
# chance to find out *who* logged out.
user = getattr(request, 'user', None)
if hasattr(user, 'is_authenticated') and not user.is_authenticated():
user = None
user_logged_out.send(sender=user.__class__, request=request, user=user)
request.session.flush()
if hasattr(request, 'user'):
from django.contrib.auth.models import AnonymousUser
request.user = AnonymousUser()