bpo-36019: Use pythontest.net instead of example.com in network tests (GH-11941)

(cherry picked from commit a40681dd5db8deaf05a635eecb91498dac882aa4)

Co-authored-by: Stéphane Wirtel <stephane@wirtel.be>
diff --git a/Lib/test/test_urllib2net.py b/Lib/test/test_urllib2net.py
index 1aa64cb..0f43d71 100644
--- a/Lib/test/test_urllib2net.py
+++ b/Lib/test/test_urllib2net.py
@@ -84,7 +84,7 @@
     def test_close(self):
         # calling .close() on urllib2's response objects should close the
         # underlying socket
-        url = "http://www.example.com/"
+        url = support.TEST_HTTP_URL
         with support.transient_internet(url):
             response = _urlopen_with_retry(url)
             sock = response.fp
@@ -173,7 +173,7 @@
                     "http://www.pythontest.net/elsewhere/#frag")
 
     def test_custom_headers(self):
-        url = "http://www.example.com"
+        url = support.TEST_HTTP_URL
         with support.transient_internet(url):
             opener = urllib.request.build_opener()
             request = urllib.request.Request(url)
@@ -259,7 +259,7 @@
 class TimeoutTest(unittest.TestCase):
     def test_http_basic(self):
         self.assertIsNone(socket.getdefaulttimeout())
-        url = "http://www.example.com"
+        url = support.TEST_HTTP_URL
         with support.transient_internet(url, timeout=None):
             u = _urlopen_with_retry(url)
             self.addCleanup(u.close)
@@ -267,7 +267,7 @@
 
     def test_http_default_timeout(self):
         self.assertIsNone(socket.getdefaulttimeout())
-        url = "http://www.example.com"
+        url = support.TEST_HTTP_URL
         with support.transient_internet(url):
             socket.setdefaulttimeout(60)
             try:
@@ -279,7 +279,7 @@
 
     def test_http_no_timeout(self):
         self.assertIsNone(socket.getdefaulttimeout())
-        url = "http://www.example.com"
+        url = support.TEST_HTTP_URL
         with support.transient_internet(url):
             socket.setdefaulttimeout(60)
             try:
@@ -290,7 +290,7 @@
             self.assertIsNone(u.fp.raw._sock.gettimeout())
 
     def test_http_timeout(self):
-        url = "http://www.example.com"
+        url = support.TEST_HTTP_URL
         with support.transient_internet(url):
             u = _urlopen_with_retry(url, timeout=120)
             self.addCleanup(u.close)