[1.6.x] Fixed #22071 -- Added a warning regarding override_settings and aliasing.

    the original ``LoginTestCase`` is still equally affected by the

    decorator.

    Finally, avoid aliasing your settings as module-level constants as

    ``override_settings()`` won't work on such values since they are

    only evaluated the first time the module is imported.

You can also simulate the absence of a setting by deleting it after settings

have been overriden, like this::