Most of these checks are still there in tests where we are checking for older Django versions. Are we keeping them for a reason? Some Examples [1](https://github.com/tomchristie/django-rest-framework/blob/master/tests/test_request.py#L204), [2](https://github.com/tomchristie/django-rest-framework/blob/master/tests/test_generics.py#L161), [3](https://github.com/tomchristie/django-rest-framework/blob/master/rest_framework/test.py#L226) ... If we do not need these checks, I can submit a PR.