---
upgrade:
  - |
    The default value of ``SESSION_ENGINE`` is changed to
    ``django.contrib.sessions.backends.cache``
    so that a cache-based session backend is used.

    The default cache back-end is set to the memcached backend
    ``django.core.cache.backends.memcached.MemcachedCache``
    from the local-memory backend
    considering multi-process web server deployments.

    They are settings which horizon recommends for a long time
    but we have not use them by default.

    If your deployment uses the signed-cookies as a session engine,
    ensure that ``SESSION_ENGINE`` is configured to
    ``django.contrib.sessions.backends.signed_cookies``
    before upgrading horizon to Stein release.
    If your deployment uses the cached session engine and
    your cache backend depends on horizon default setting,
    ensure to ``CACHES`` setting to use the local-memory backend.
