Fixed #24468 -- Made signed cookies cache backend resilient to unpickling exceptions.

                # This doesn't handle non-default expiry dates, see #19201

                max_age=settings.SESSION_COOKIE_AGE,

                salt='django.contrib.sessions.backends.signed_cookies')

        except (signing.BadSignature, ValueError):

        except Exception:

            # BadSignature, ValueError, or unpickling exceptions. If any of

            # these happen, reset the session.

            self.create()

        return {}

from django.contrib.sessions.exceptions import InvalidSessionKey

from django.contrib.sessions.middleware import SessionMiddleware

from django.contrib.sessions.models import Session

from django.contrib.sessions.serializers import (

    JSONSerializer, PickleSerializer,

)

from django.core import management

from django.core.cache import caches

from django.core.cache.backends.base import InvalidCacheBackendError

    def test_actual_expiry(self):

        # The cookie backend doesn't handle non-default expiry dates, see #19201

        super(CookieSessionTests, self).test_actual_expiry()

    def test_unpickling_exception(self):

        # signed_cookies backend should handle unpickle exceptions gracefully

        # by creating a new session

        self.assertEqual(self.session.serializer, JSONSerializer)

        self.session.save()

        self.session.serializer = PickleSerializer

        self.session.load()