fix for custom pipeline configuration (#29004)

* fix for custom pipeline configuration

* fix for custom pipelines

* remove extra exception

* added test for custom pipelines extra tag

* format with ruff

* limit extra tag for first time only

* format with ruff

* improve tests for custom pipelines

tests/pipelines/test_pipelines_common.py

@@ -925,6 +925,24 @@ class DynamicPipelineTester(unittest.TestCase):
         # Can't make an isinstance check because the new_classifier is from the PairClassificationPipeline class of a
         # dynamic module
         self.assertEqual(new_classifier.__class__.__name__, "PairClassificationPipeline")
+        # check for tag exitence, tag needs to be added when we are calling a custom pipeline from the hub
+        # useful for cases such as finetuning
+        self.assertDictEqual(
+            new_classifier.model.config.custom_pipelines,
+            {
+                "pair-classification": {
+                    "impl": f"{USER}/test-dynamic-pipeline--custom_pipeline.PairClassificationPipeline",
+                    "pt": ("AutoModelForSequenceClassification",),
+                    "tf": (),
+                }
+            },
+        )
+        # test if the pipeline still works after the model is finetuned
+        # (we are actually testing if the pipeline still works from the final repo)
+        # this is where the user/repo--module.class is used for
+        new_classifier.model.push_to_hub(repo_name=f"{USER}/test-pipeline-for-a-finetuned-model", token=self._token)
+        del new_classifier  # free up memory
+        new_classifier = pipeline(model=f"{USER}/test-pipeline-for-a-finetuned-model", trust_remote_code=True)
 
         results = classifier("I hate you", second_text="I love you")
         new_results = new_classifier("I hate you", second_text="I love you")