src/transformers/utils/hub.py/extract_commit_hash
def extract_commit_hash(resolved_file: Optional[str], commit_hash: Optional[str]):
    """
    Extracts the commit hash from a resolved filename toward a cache file.
    """
    if resolved_file is None or commit_hash is not None:
        return commit_hash
    resolved_file = str(Path(resolved_file).as_posix())
    search = re.search(r"snapshots/([^/]+)/", resolved_file)
    if search is None:
        return None
    commit_hash = search.groups()[0]
    return commit_hash if REGEX_COMMIT_HASH.match(commit_hash) else None