fix beam search bug in tf as well (#4745)

src/transformers/modeling_tf_utils.py

@@ -1218,7 +1218,7 @@ class TFPreTrainedModel(tf.keras.Model, TFModelUtilsMixin):
                 continue
             # test that beam scores match previously calculated scores if not eos and batch_idx not done
             if eos_token_id is not None and all(
-                (token_id % vocab_size).numpy().item() is not eos_token_id for token_id in next_tokens[batch_idx]
+                (token_id % vocab_size).numpy().item() != eos_token_id for token_id in next_tokens[batch_idx]
             ):
                 assert tf.reduce_all(
                     next_scores[batch_idx, :num_beams] == tf.reshape(beam_scores, (batch_size, num_beams))[batch_idx]

src/transformers/modeling_utils.py

@@ -1528,7 +1528,7 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin):
 
             # test that beam scores match previously calculated scores if not eos and batch_idx not done
             if eos_token_id is not None and all(
-                (token_id % vocab_size).item() is not eos_token_id for token_id in next_tokens[batch_idx]
+                (token_id % vocab_size).item() != eos_token_id for token_id in next_tokens[batch_idx]
             ):
                 assert torch.all(
                     next_scores[batch_idx, :num_beams] == beam_scores.view(batch_size, num_beams)[batch_idx]