breaking: checkpoint the inner estimator only

bob/pipelines/wrappers.py

@@ -570,8 +570,10 @@ class CheckpointWrapper(BaseWrapper, TransformerMixin):
         if is_estimator_stateless(self.estimator):
             return self
         with open(self.model_path, "rb") as f:
-            model = cloudpickle.load(f)
-            self.__dict__.update(model.__dict__)
+            estimator = cloudpickle.load(f)
+            # we don't do self.estimator = estimator, because self.estimator
+            # might be used elsewhere
+            self.estimator.__dict__.update(estimator.__dict__)
             return self
 
     def save_model(self):
@@ -579,7 +581,7 @@ class CheckpointWrapper(BaseWrapper, TransformerMixin):
             return self
         os.makedirs(os.path.dirname(self.model_path), exist_ok=True)
         with open(self.model_path, "wb") as f:
-            cloudpickle.dump(self, f)
+            cloudpickle.dump(self.estimator, f)
         return self