The default urlparse.urljoin behavior look strange
    Standard urlparse.urljoin('http://a.com/foo', '/bar')
    Expect: http://a.com/foo/bar
    Actually: http://a.com/bar

    This function fix that.

def urljoin(*urls):
    """
    The default urlparse.urljoin behavior look strange
    Standard urlparse.urljoin('http://a.com/foo', '/bar')
    Expect: http://a.com/foo/bar
    Actually: http://a.com/bar

    This function fix that.
    """
    return reduce(urlparse.urljoin, [u.strip('/')+'/' for u in urls if u.strip('/')], '').rstrip('/')