Fixed small regression from 51aa0003.

        ser_fmts = serializers.get_public_serializer_formats() if ser_fmt is None else [ser_fmt]

        # Check kept for backwards-compatibility; it doesn't look very useful.

        if '.' in fixture_name:

        if '.' in os.path.basename(fixture_name):

            raise CommandError(

                    "Problem installing fixture '%s': %s is not a known "

                    "serialization format." % tuple(fixture_name.rsplit('.')))