In [this commit](https://github.com/jschneier/django-storages/commit/7cb67d57bfa9df3a28ca631da057b870a1cf201d), django-storages moved the clean_name function to storages.utils, but kept compatibility with the self._clean_name invocation. In [this commit](https://github.com/jschneier/django-storages/commit/ed63bd8481872193ef5138bdb04498a008feda1f), support for the invocation of clean_name through self._clean_name was removed. I'll create a pull request for this issue.