Revert "Fixed #22867 -- Memoized django.utils.version.get_git_changeset()."

This reverts commit 80f4487 temporarily, because that commit prevented
the djangoproject.com server from building the docs, because it still
uses Python 2.6.
Refs #12663 -- Added tests for methods in db.models.options.

Thanks Russell Keith-Magee and Tim Graham for reviews.
Fixed #22863: Improve clarity of makemigrations for non-db params
Fixed #22874: Document that AUTH_USER_MODEL must be in first migration
Swapped placeholders in [sql]migrate command error
Fixed #22836 -- Linked tutorial05 to the right section of tutorial04.
Fixed #22862 -- Added --noinput option to makemigrations.

Thanks artortenburger for the report.
Moved a line outside of try/except to prevent an error in finally.

Thanks Ian Foote.
Fixed #22514 -- Prevented indexes on virtual fields [postgres].
Fixed #22782 -- Added i18n attr to Sitemap class

It makes possible to have your sitemap in multiple languages when
using i18n in URLs.
Added HTTP 308 status and its description.
Fixed #22838 -- Deprecated ModelChoiceField.cache_choices.

Undocumented, untested and probably not even useful feature.
Fixed test from refs #22782.
Added refs #22514 to 1.6.6 release notes.
Prevented evaluation of a possible lazy message

As far as possible, message evaluation should not happen in field
__init__ (often run at import time).
Fixed #22793 -- Updated import location for GeometryColumns in tests

The old location was removed in cebd8753c6.
Thanks Aymeric Augustin for the report.
Removed some apps from ALWAYS_INSTALLED_APPS
Fixed #22867 -- Memoized django.utils.version.get_git_changeset().

This follows commits 80f4487 and 01399fa; original patch had to be
reverted because it wasn't Python 2.6 compatible and we need it to
be in order to build docs on the djangoproject.com server.

This fix should be replaced by @lru_cache as soon as we drop
Python 2.6 compatibility.

Thanks Florian Apolloner for the review and Alexander Schepanovski
for the original patch.
Fixed #22875: Optimizer did not take through= into account.
Include swapped apps in autodetector state