'Include all fields. Reset all previously calls of .only() or
.exclude(). ::
post = BlogPost.objects.exclude(\'comments\').all_fields()
.. versionadded:: 0.5'

def all_fields(self):

    queryset = self.clone()
    queryset._loaded_fields = QueryFieldList(always_include=queryset._loaded_fields.always_include)
    return queryset
