Update tiktoken.py

tiktoken.py

@@ -173,11 +173,15 @@ class TiktokenTokenizerWrapper(PreTrainedTokenizer):
         Pinning default Chat ML template in case defaults change.
         """
         template = (
-            "{% set system_message = '' %}"
-            '{% if USE_DEFAULT_PROMPT == true %}'
-            "{{'<|im_start|>system\n' + 'DEFAULT_SYSTEM_PROMPT'}}"
+            "{% if messages[0]['role'] == 'system' %}"
+            "{% set loop_messages = messages[1:] %}"  # Extract system message if it's present
+            "{% set system_message = messages[0]['content'] %}"
+            "{% elif USE_DEFAULT_PROMPT == true and not 'system' in messages[0]['role']%}"
+            "{% set loop_messages = messages %}"  # Extract system message if it's present
+            "{% set system_message = 'DEFAULT_SYSTEM_PROMPT' %}"
+            "{{'<|im_start|>system\n' + system_message}}"
             '{% endif %}'
-            '{% for message in messages %}'
+            '{% for message in loop_messages %}'
             "{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}"
             '{% if (add_generation_prompt == true) %}'
             "{{'<|im_start|>' + 'assistant' + '\n'}}"