Use commit hash to look in cache instead of calling head (#18534)

* Use commit hash to look in cache instead of calling head

* Add tests

* Add attr for local configs too

* Stupid typos

* Fix tests

* Update src/transformers/utils/hub.py

Co-authored-by: Julien Chaumond <julien@huggingface.co>

* Address Julien's comments

Co-authored-by: Julien Chaumond <julien@huggingface.co>

tests/models/auto/test_tokenization_auto.py

@@ -48,6 +48,7 @@ from transformers.testing_utils import (
     DUMMY_DIFF_TOKENIZER_IDENTIFIER,
     DUMMY_UNKNOWN_IDENTIFIER,
     SMALL_MODEL_IDENTIFIER,
+    RequestCounter,
     require_tokenizers,
     slow,
 )
@@ -213,6 +214,7 @@ class AutoTokenizerTest(unittest.TestCase):
     def test_get_tokenizer_config(self):
         # Check we can load the tokenizer config of an online model.
         config = get_tokenizer_config("bert-base-cased")
+        _ = config.pop("_commit_hash", None)
         # If we ever update bert-base-cased tokenizer config, this dict here will need to be updated.
         self.assertEqual(config, {"do_lower_case": False})
 
@@ -340,3 +342,13 @@ class AutoTokenizerTest(unittest.TestCase):
             EnvironmentError, r"aaaaaa is not a valid git identifier \(branch name, tag name or commit id\)"
         ):
             _ = AutoTokenizer.from_pretrained(DUMMY_UNKNOWN_IDENTIFIER, revision="aaaaaa")
+
+    def test_cached_tokenizer_has_minimum_calls_to_head(self):
+        # Make sure we have cached the tokenizer.
+        _ = AutoTokenizer.from_pretrained("hf-internal-testing/tiny-random-bert")
+        with RequestCounter() as counter:
+            _ = AutoTokenizer.from_pretrained("hf-internal-testing/tiny-random-bert")
+            self.assertEqual(counter.get_request_count, 0)
+            # We still have one extra call because the model does not have a added_tokens.json file
+            self.assertEqual(counter.head_request_count, 2)
+            self.assertEqual(counter.other_request_count, 0)