fix stop words

src/llmtuner/data/template.py

@@ -1,4 +1,5 @@
 import tiktoken
+from copy import deepcopy
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, Dict, List, Optional, Tuple, Union
 
@@ -223,19 +224,20 @@ def get_template_and_fix_tokenizer(
     template = templates.get(name, None)
     assert template is not None, "Template {} does not exist.".format(name)
 
+    stop_words = deepcopy(template.stop_words)
     if template.replace_eos:
-        if not template.stop_words:
+        if not stop_words:
             raise ValueError("Stop words are required to replace the EOS token.")
 
-        tokenizer.eos_token = template.stop_words.pop(0)
+        tokenizer.eos_token = stop_words.pop(0)
         logger.info("Replace eos token: {}".format(tokenizer.eos_token))
 
-    if template.stop_words:
+    if stop_words:
         tokenizer.add_special_tokens(
-            dict(additional_special_tokens=template.stop_words),
+            dict(additional_special_tokens=stop_words),
             replace_additional_special_tokens=False
         )
-        logger.info("Add {} to stop words.".format(",".join(template.stop_words)))
+        logger.info("Add {} to stop words.".format(",".join(stop_words)))
 
     return template