Return the root path of a path relative to an absolute path.

    Example:

    @param absolute_path: an absolute path that is ended by the specified
        relative path.

    @param relative_path: a relative path that ends the specified absolute
        path.

    @return: the root path of the relative path.

def find_root_path(absolute_path, relative_path):
    """
    Return the root path of a path relative to an absolute path.

    Example:

    @param absolute_path: an absolute path that is ended by the specified
        relative path.

    @param relative_path: a relative path that ends the specified absolute
        path.

    @return: the root path of the relative path.
    """
    _absolute_path = os.path.normpath(absolute_path)
    _relative_path = os.path.normpath(relative_path)

    index = _absolute_path.rfind(_relative_path)
    if index == -1 or len(_relative_path) + index < len(_absolute_path):
        raise ValueError('The relative path does not end the specified absolute path')

    return _absolute_path[:index]