Path.resolve can not resolve urls

[econwang]

The relative_url function in output.py:

    link_str = str(entity)
    link = BeautifulSoup(link_str, features="html.parser").a
    if link is not None:
        link_path = str(pathlib.Path(str(link["href"])).resolve())
    else:
        link_path = link_str

will raise error for urls, such as INTRINSIC_MODS in settings.py.