fixup! default add_special_tokens as unset

lm_eval/models/huggingface.py

@@ -897,7 +897,7 @@ class HFLM(TemplateLM):
             elif self.add_bos_token is not None:
                 add_special_tokens = {"add_special_tokens": self.add_bos_token}
             else:
-                add_special_tokens = {"add_special_tokens": True}
+                add_special_tokens = {}
 
         encoding = self.tokenizer(
             strings,

lm_eval/models/utils.py

@@ -884,4 +884,4 @@ def postprocess_generated_text(
 
 
 def bos_already_added(sequence: str, bos_string: Optional[str]):
-    return sequence[0] == bos_string
+    return sequence.startswith(bos_string) if bos_string is not None else False