Update metrics/bleu.py

metrics/bleu.py

@@ -1,5 +1,6 @@
 # Copied from https://github.com/huggingface/datasets/blob/76bb45964df1e62d1411b0a9e9fc673e9a791c9a/metrics/sacrebleu/sacrebleu.py
 
+from copy import deepcopy
 from sacrebleu.metrics import BLEU
 
 
@@ -15,6 +16,7 @@ def compute_bleu(
 ):
     references_per_prediction = len(references[0])
     if any(len(refs) != references_per_prediction for refs in references):
+        references = deepcopy(references)
         max_references_per_prediction = max(len(refs) for refs in references)
         for refs in references:
             refs.extend([None] * (max_references_per_prediction - len(refs)))