returns the relative path of the current directory to the git
    repository.
    This path will be added the 'filename' path to find the file.
    It current_dir is the git root, this function returns an empty string.

    Keyword Arguments:
        <none>

    Returns:
        str -- relative path of the current dir to git root dir
               empty string if current dir is the git root dir

def _delta_dir():
    """returns the relative path of the current directory to the git
    repository.
    This path will be added the 'filename' path to find the file.
    It current_dir is the git root, this function returns an empty string.

    Keyword Arguments:
        <none>

    Returns:
        str -- relative path of the current dir to git root dir
               empty string if current dir is the git root dir
    """
    repo = Repo()
    current_dir = os.getcwd()
    repo_dir = repo.tree().abspath
    delta_dir = current_dir.replace(repo_dir, '')
    if delta_dir:
        return delta_dir + '/'
    else:
        return ''