bpo-40275: Move transient_internet from test.support to socket_helper (GH-19711)

diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 6b7a9de..e95487b 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -1629,7 +1629,7 @@
         # Default settings: requires a valid cert from a trusted CA
         import ssl
         support.requires('network')
-        with support.transient_internet('self-signed.pythontest.net'):
+        with socket_helper.transient_internet('self-signed.pythontest.net'):
             h = client.HTTPSConnection('self-signed.pythontest.net', 443)
             with self.assertRaises(ssl.SSLError) as exc_info:
                 h.request('GET', '/')
@@ -1639,7 +1639,7 @@
         # Switch off cert verification
         import ssl
         support.requires('network')
-        with support.transient_internet('self-signed.pythontest.net'):
+        with socket_helper.transient_internet('self-signed.pythontest.net'):
             context = ssl._create_unverified_context()
             h = client.HTTPSConnection('self-signed.pythontest.net', 443,
                                        context=context)
@@ -1653,7 +1653,7 @@
     def test_networked_trusted_by_default_cert(self):
         # Default settings: requires a valid cert from a trusted CA
         support.requires('network')
-        with support.transient_internet('www.python.org'):
+        with socket_helper.transient_internet('www.python.org'):
             h = client.HTTPSConnection('www.python.org', 443)
             h.request('GET', '/')
             resp = h.getresponse()
@@ -1667,7 +1667,7 @@
         import ssl
         support.requires('network')
         selfsigned_pythontestdotnet = 'self-signed.pythontest.net'
-        with support.transient_internet(selfsigned_pythontestdotnet):
+        with socket_helper.transient_internet(selfsigned_pythontestdotnet):
             context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
             self.assertEqual(context.verify_mode, ssl.CERT_REQUIRED)
             self.assertEqual(context.check_hostname, True)
@@ -1699,7 +1699,7 @@
         # We feed a "CA" cert that is unrelated to the server's cert
         import ssl
         support.requires('network')
-        with support.transient_internet('self-signed.pythontest.net'):
+        with socket_helper.transient_internet('self-signed.pythontest.net'):
             context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
             context.load_verify_locations(CERT_localhost)
             h = client.HTTPSConnection('self-signed.pythontest.net', 443, context=context)