[SPM] Patch spm Llama and T5 (#25656)

* hot fix

* only encode with string prefix if starts with prefix

* styling

* add a new test

* fixup

tests/models/llama/test_tokenization_llama.py

@@ -546,6 +546,15 @@ class LlamaIntegrationTest(unittest.TestCase):
         decoded_tokens = tokenizer.decode(input_ids)
         self.assertEqual(decoded_tokens, " <s> Hello<s> how")
 
+    def test_some_edge_cases(self):
+        tokenizer = LlamaTokenizer.from_pretrained("huggyllama/llama-7b", legacy=False)
+
+        sp_tokens = tokenizer.sp_model.encode("<s>>", out_type=str)
+        self.assertEqual(sp_tokens, ["<", "s", ">>"])
+        tokens = tokenizer.tokenize("<s>>")
+        self.assertNotEqual(sp_tokens, tokens)
+        self.assertEqual(tokens, ["<s>", ">"])
+
 
 @require_sentencepiece
 @require_tokenizers