Algoritmo para desencurtar URLs obtido do stackoverflow seguido da refatoração que fiz.

unshorten_url.py

# Código original
import httplib
import urlparse

def unshorten_url(url):
    parsed = urlparse.urlparse(url)
    h = httplib.HTTPConnection(parsed.netloc)
    resource = parsed.path
    if parsed.query != "":
        resource += "?" + parsed.query
    h.request('HEAD', resource)
    response = h.getresponse()
    if response.status/100 == 3 and response.getheader('Location'):
        # changed to process chains of short urls
        return unshorten_url(response.getheader('Location'))
    else:
        return url


# Código refatorado
from urlparse import urlparse
from httplib import HTTPSConnection, HTTPConnection

def unshorten_url(url):
    parsed_url = urlparse(url)
    if parsed_url.scheme == 'https':
        host = HTTPSConnection(parsed_url.netloc)
    else:
        host = HTTPConnection(parsed_url.netloc)

    resource = parsed_url.path
    if parsed_url.query:
        resource = '?'.join((resource, parsed_url.query))

    host.request('HEAD', resource)
    response = host.getresponse()
    location = response.getheader('Location')
    if response.status/100 == 3 and location:
        return unshorten_url(location)
    else:
        return url