Return VCS root directory path
    Return None if path is not within a supported VCS repository

def get_vcs_root(path):
    """Return VCS root directory path
    Return None if path is not within a supported VCS repository"""
    previous_path = path
    while get_vcs_info(path) is None:
        path = abspardir(path)
        if path == previous_path:
            return
        else:
            previous_path = path
    return osp.abspath(path)