I got a similar problem but here the ISP returned an error/search page
and a "302 Found". test_urllibnet.test_bad_address() failed with
"AssertionError: IOError not raised by urlopen"

>>> import http.client
>>> conn = http.client.HTTPConnection("www.somerandominvalidpage.edu")
>>> conn.request("GET", "/")
>>> r1 = conn.getresponse()
>>> r1.status, r1.reason
(302, 'Found')

test_xmlrpc_net failed for the same reason (see #6027).