def isKnownTrackingBranch(remote: str, b: str) -> bool:
    """ Returns true if the given branch is a known remote branch that we
        should look out for when computing the boundary of the commit graph. """
    remote_prefix = f'{remote}/'
    if not b.startswith(remote_prefix):
        return False
    known_prefixes = set(['llvm.org', 'apple', 'internal', 'swift'])
    return b[len(remote_prefix):].split('/')[0] in known_prefixes