#17564: skip test_bad_address unless the tests are run with -unetwork/-uall.

Lib/test/test_urllib2_localnet.py

@@ -524,6 +524,11 @@ def test_geturl(self):
     def test_bad_address(self):
         # Make sure proper exception is raised when connecting to a bogus
         # address.
+
+        # as indicated by the comment below, this might fail with some ISP,
+        # so we run the test only when -unetwork/-uall is specified to
+        # mitigate the problem a bit (see #17564)
+        support.requires('network')
         self.assertRaises(IOError,
                           # Given that both VeriSign and various ISPs have in
                           # the past or are presently hijacking various invalid