from urllib.parse import urlunparse, urlparse
from urllib.request import urlopen
url = 'http://сайт.рф'
scheme, netloc, path, params, query, fragment = urlparse(url)
url = urlunparse((scheme, netloc.encode('idna').decode('utf8'), path, params, query, fragment))
r = urlopen(url)
print(r.read()[0:50])