causes ipython 0.13 trouble

#!/usr/bin/env python

import xmlrpclib
from pprint import pprint

archive_preferences = ['.tar.bz2', '.tar.gz', '.tgz', '.zip']

def package_url(package_name):
    client = xmlrpclib.ServerProxy('http://pypi.python.org/pypi')
    version = client.package_releases(package_name)
    print 'version:', version
    urls = client.release_urls('pandas', version[0])
    possible_url = {}
    for url_num, url_entry in enumerate(urls):
        print url_num, url_entry['filename']
        for extension in archive_preferences:
            if extension in url_entry['filename']:
                print 'match:', extension, url_entry['filename']
                possible_url[extension] = url_num
    if not possible_url:
        logging.warning('Unable to find a suitable archive for %s', package_name)
        return None
    print 'possible_url', possible_url
    #[urls[possible_url[key]]['filename'] for key in possible_url]
    entry_num = None

    for pref in archive_preferences:
        if pref in possible_url:
            entry_num = possible_url[pref]
            break
    assert entry_num

    return urls[entry_num]

def try_me():
    package_data = package_url('pandas')
    print package_data

if __name__ == '__main__':
    try_me()