Fixed #20819 -- Return 404 instead of 500 error when ``staticfiles`` view is used in production.

    from urllib import unquote

from django.conf import settings

from django.core.exceptions import ImproperlyConfigured

from django.http import Http404

from django.views import static

    It uses the django.views.static view to serve the found files.

    """

    if not settings.DEBUG and not insecure:

        raise ImproperlyConfigured("The staticfiles view can only be used in "

                                   "debug mode or if the --insecure "

                                   "option of 'runserver' is used")

        raise Http404

    normalized_path = posixpath.normpath(unquote(path)).lstrip('/')

    absolute_path = finders.find(normalized_path)

    if not absolute_path:

    **insecure**. This is only intended for local development, and should

    **never be used in production**.

.. versionchanged:: 1.7

    Will now raise an :exc:`~django.http.Http404` exception instead of

    :exc:`~from django.core.exceptions.ImproperlyConfigured` when

    :setting:`DEBUG` is ``True``.

.. note::

    To guess the served files' content types, this view relies on the

* Loading empty fixtures emits a ``RuntimeWarning`` rather than raising

  :class:`~django.core.management.CommandError`.

* :view:`~django.contrib.staticfiles.views.serve` will now raise an

  :exc:`~django.http.Http404` exception instead of

  :exc:`~from django.core.exceptions.ImproperlyConfigured` when :setting:`DEBUG`

  is ``True``. This change removes the need to conditionally add the view to

  your root URLconf, which in turn makes it safe to reverse by name. It also

  removes the ability for visitors to generate spurious HTTP 500 errors by

  requesting static files that don't exist or haven't been collected yet.

Features deprecated in 1.7

==========================

        settings.DEBUG = False

    def test_disabled_serving(self):

        six.assertRaisesRegex(self, ImproperlyConfigured, 'The staticfiles view '

            'can only be used in debug mode ', self._response, 'test.txt')

        self.assertFileNotFound('test.txt')

class TestServeStaticWithDefaultURL(TestServeStatic, TestDefaults):