Django gravatar url by template filter

gravatar.py

# coding: utf-8
import hashlib
import httplib
import urllib
from django import template
from django.conf import settings

register = template.Library()

GRAVATAR_DOMAIN = "gravatar.com"
GRAVATAR_PATH = "/avatar/"


@register.filter(name="show_gravatar_url")
def show_gravatar_url(email, size=48):
    """ Uses to get correct url to gravatar email. """
    if not email is None:
        query = urllib.urlencode({
            'gravatar_id': hashlib.md5(email).hexdigest(),
            'size': str(size),
            'default': '/'
        })
        full_path = "%s?%s" % (GRAVATAR_PATH, query)

        # Create connection and test for 302 redirect
        conn = httplib.HTTPConnection(GRAVATAR_DOMAIN)
        conn.request('HEAD', full_path)
        response = conn.getresponse()

        if not response.status == 302:
            return "http://%s%s" % (GRAVATAR_DOMAIN, full_path)
    return "%s%s" % (settings.STATIC_URL, "/images/avatar.png")