Fixed #19746 -- Allow deserialization of pk-less data
Fixed #19810 -- MemcachedCache now uses pickle.HIGHEST_PROTOCOL
Fixed minor rst formatting glitch.
Fixed #16302 -- Ensure contrib.comments is IPv6 capable

Changed the ip_address field for Comment to GenericIPAddressField. Added
instructions to the release notes on how to update the schema of existing
databases.
Merge pull request #819 from erikr/master

Fixed #16302 -- Ensured contrib.comments is IPv6 capable.
Fixed #9084 - Best approach for an OS to atomically rename the session file.
Fixed #19253 -- Extracted template cache key building logic

Introduced a public function
django.core.cache.utils.make_template_fragment_key
Thanks @chrismedrela for fruitful cooperation.
Fixes #19763 - LocaleMiddleware should check for supported languages in settings.LANGUAGE_CODE
Loaded cycle and firstof from future in built-in templates. Refs #17906.

This was missing from f49e9a517f2fdc1d9ed7ac841ace77636cbd6747.
Merge pull request #717 from slurms/ticket_19746

Fixed #19746 -- Allow deserialization of pk-less data
Test case and docs for custom context data in feeds

Thanks Paul Winkler for the initial patch. (Ref #18112).
Added a note about Feed.get_context_data to the 1.6 release notes.
Fixed creation of html docs on python 3.

Thanks to Alan Lu for the report and the patch.
Fixed #15849 -- Made IfChanged node thread safe.

Previously, the ifchanged node stored state on `self._last_seen`,
thereby giving undesired results when the node is reused by another
thread at the same time (e.g. globally caching a Template object).

Thanks to akaihola for the report and Diederik van der Boor and
Bas Peschier for the patch.
Fixed #17320 -- Added whitespace validation to the Site.domain field
Fixed #19890 -- ifchanged templatetag rendered its content twice

The content of ifchanged template tag was rendered twice: first time, to
compare it with the previous value and the second time, to return the
rendered output.
Fixed #19394 --Added note about auth forms and custom user models.
Fix documentation :mod: role in Syndication feed text.
Merge pull request #832 from chrismedrela/ticket19890

Fixed #19890 -- ifchanged templatetag rendered its content twice
Fixed #19688 -- Allow model subclassing with a custom metaclass using six.with_metaclass