def __init__(self, source_address=None, debuglevel=0):
    urllib2.HTTPHandler.__init__(self, debuglevel)
    self.http_class = functools.partial(httplib.HTTPConnection,
            source_address=source_address)

def http_open(self, req):
    return self.do_open(self.http_class, req)

(...other code....)

def _call(path, args, headers=None, url=None, data=None):
    """
    Make a request to the Piwik site. It is up to the caller to format
    arguments, to embed authentication, etc.
    """
    if url is None:
        url = config.options.piwik_url
    headers = headers or {}

    if data is None:
        # If Content-Type isn't defined, PHP do not parse the request's body.
        headers['Content-type'] = 'application/x-www-form-urlencoded'
        data = urllib.urlencode(args)
    elif not isinstance(data, basestring) and headers['Content-type'] == 'application/json':
        data = json.dumps(data)

    handler = BoundHTTPHandler(source_address=('127.0.0.1', 0))
    opener = urllib2.build_opener(handler)
    urllib2.install_opener(opener)

    headers['User-Agent'] = 'Piwik/LogImport'
    request = urllib2.Request(url + path, data, headers)
    response = urllib2.urlopen(request)
    result = response.read()
    response.close()
    return result