Fix hp search for non sigopt backends (huggingface#13897)

src/transformers/trainer.py

@@ -1238,7 +1238,11 @@ def train(
         self.callback_handler.lr_scheduler = self.lr_scheduler
         self.callback_handler.train_dataloader = train_dataloader
         self.state.trial_name = self.hp_name(trial) if self.hp_name is not None else None
-        self.state.trial_params = hp_params(trial.assignments) if trial is not None else None
+        if trial is not None:
+            assignments = trial.assignments if self.hp_search_backend == HPSearchBackend.SIGOPT else trial
+            self.state.trial_params = hp_params(assignments)
+        else:
+            self.state.trial_params = None
         # This should be the same if the state has been saved but in case the training arguments changed, it's safer
         # to set this after the load.
         self.state.max_steps = max_steps