code: def raw_field_definition_proxy_post_save(sender, instance, raw, **kwargs):
      
      if raw:
          model_class = instance.content_type.model_class()
          opts = model_class._meta
          if opts.proxy and opts.concrete_model is sender:
              field_definition_post_save(
                  sender=model_class, instance=instance.type_cast(), raw=raw,
                  **kwargs
              )
docs: When proxy field definitions are loaded from a fixture they're not
      passing through the `field_definition_post_save` signal. Make sure they
      are.