Fixed #22835 -- Deprecated NoArgsCommand.
Fixed #22867 -- Memoized django.utils.version.get_git_changeset().

This improves pickling speed in prelease versions of Django; refs #21430.
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.