          models.URLField: URLField,
          models.GenericIPAddressField: IPAddressField,
      }
      if ModelDurationField is not None:
          serializer_field_mapping[ModelDurationField] = DurationField
      serializer_related_field = PrimaryKeyRelatedField
      serializer_url_field = HyperlinkedIdentityField
 
</s> remove         if django.VERSION < (1, 5):
            # django field doesn't have allow_folders, allow_files kwargs
            field = DjangoFilePathField(
                path, match=match, recursive=recursive, required=required
            )
        else:
            field = DjangoFilePathField(
                path, match=match, recursive=recursive, allow_files=allow_files,
                allow_folders=allow_folders, required=required
            )
 </s> add         field = get_filepathfield(
            path, match=match, recursive=recursive, allow_files=allow_files,
            allow_folders=allow_folders, required=required
        ) </s> remove     parse_duration, unicode_repr, unicode_to_repr
 </s> add     parse_duration, unicode_repr, unicode_to_repr, get_filepathfield
        models.FilePathField: FilePathField,
          models.URLField: URLField,
          models.GenericIPAddressField: IPAddressField,
        models.FilePathField: FilePathField,
      }
      if ModelDurationField is not None:
          serializer_field_mapping[ModelDurationField] = DurationField
      serializer_related_field = PrimaryKeyRelatedField
      serializer_url_field = HyperlinkedIdentityField
keep add keep keep keep keep keep
 fix bugs, move version branching to compat, update ModelSerializer mapping 
rest_framework/serializers.py