Fixed #26152 -- Documented how to avoid django.setup() deadlock in standalone scripts.

standalone. When invoked by your Web server, or through :doc:`django-admin

</ref/django-admin>`, Django will handle this for you.

.. admonition:: ``django.setup()`` may only be called once.

    Therefore, avoid putting reusable application logic in standalone scripts

    so that you have to import from the script elsewhere in your application.

    If you can't avoid that, put the call to ``django.setup()`` inside an

    ``if`` block::

        if __name__ == '__main__':

            import django

            django.setup()

.. seealso::

    :doc:`The Settings Reference </ref/settings>`