Fixed #23295 -- Removed unnecessary fix_location_header requset.get_host() check

https://code.djangoproject.com/ticket/23295
I assume that calling `get_host()` on an empty `HttpRequest()` raises an error of some kind, so this test works by implicitly asserting that no error was raised? If so, a comment to indicate what error would be raised if `get_host()` were called would make the test much more comprehensible.