Fixed #19489 -- Documented host parameter of assertRedirects().

    You can use this as a context manager in the same way as

    :meth:`~SimpleTestCase.assertTemplateUsed`.

.. method:: SimpleTestCase.assertRedirects(response, expected_url, status_code=302, target_status_code=200, msg_prefix='', fetch_redirect_response=True)

.. method:: SimpleTestCase.assertRedirects(response, expected_url, status_code=302, target_status_code=200, host=None, msg_prefix='', fetch_redirect_response=True)

    Asserts that the response return a ``status_code`` redirect status, it

    redirected to ``expected_url`` (including any GET data), and the final

    page was received with ``target_status_code``.

    Asserts that the response returned a ``status_code`` redirect status,

    redirected to ``expected_url`` (including any ``GET`` data), and that the

    final page was received with ``target_status_code``.

    If your request used the ``follow`` argument, the ``expected_url`` and

    ``target_status_code`` will be the url and status code for the final

    point of the redirect chain.

    The ``host`` argument sets a default host if ``expected_url`` doesn't

    include one (e.g. ``"/bar/"``).  If ``expected_url`` is an absolute URL that

    includes a host (e.g. ``"http://testhost/bar/"``), the ``host`` parameter

    will be ignored. Note that the test client doesn't support fetching external

    URLs, but the parameter may be useful if you are testing with a custom HTTP

    host (for example, initializing the test client with

    ``Client(HTTP_HOST="testhost")``.

    .. versionadded:: 1.7

    If ``fetch_redirect_response`` is ``False``, the final page won't be