bpo-35411: Skip test_urllib2net FTP tests on Travis CI (GH-10907) (#11874)

On Travis CI, FTP tests of test_urllib2net randomly fail with "425
Security: Bad IP connecting".

(cherry picked from commit c11b3b1)

Author: vstinner

Lib/test/test_urllib2net.py

@@ -27,6 +27,13 @@ def wrapped(*args, **kwargs):
         return _retry_thrice(func, exc, *args, **kwargs)
     return wrapped
 
+# bpo-35411: FTP tests of test_urllib2net randomly fail
+# with "425 Security: Bad IP connecting" on Travis CI
+skip_ftp_test_on_travis = unittest.skipIf('TRAVIS' in os.environ,
+                                          'bpo-35411: skip FTP test '
+                                          'on Travis CI')
+
+
 # Connecting to remote hosts is flaky.  Make it more robust by retrying
 # the connection several times.
 _urlopen_with_retry = _wrap_with_retry_thrice(urllib.request.urlopen,
@@ -95,6 +102,7 @@ def setUp(self):
     # XXX The rest of these tests aren't very good -- they don't check much.
     # They do sometimes catch some major disasters, though.
 
+    @skip_ftp_test_on_travis
     def test_ftp(self):
         urls = [
             'ftp://www.pythontest.net/README',
@@ -289,13 +297,15 @@ def test_http_timeout(self):
 
     FTP_HOST = 'ftp://www.pythontest.net/'
 
+    @skip_ftp_test_on_travis
     def test_ftp_basic(self):
         self.assertIsNone(socket.getdefaulttimeout())
         with support.transient_internet(self.FTP_HOST, timeout=None):
             u = _urlopen_with_retry(self.FTP_HOST)
             self.addCleanup(u.close)
             self.assertIsNone(u.fp.fp.raw._sock.gettimeout())
 
+    @skip_ftp_test_on_travis
     def test_ftp_default_timeout(self):
         self.assertIsNone(socket.getdefaulttimeout())
         with support.transient_internet(self.FTP_HOST):
@@ -307,6 +317,7 @@ def test_ftp_default_timeout(self):
                 socket.setdefaulttimeout(None)
             self.assertEqual(u.fp.fp.raw._sock.gettimeout(), 60)
 
+    @skip_ftp_test_on_travis
     def test_ftp_no_timeout(self):
         self.assertIsNone(socket.getdefaulttimeout())
         with support.transient_internet(self.FTP_HOST):
@@ -318,6 +329,7 @@ def test_ftp_no_timeout(self):
                 socket.setdefaulttimeout(None)
             self.assertIsNone(u.fp.fp.raw._sock.gettimeout())
 
+    @skip_ftp_test_on_travis
     def test_ftp_timeout(self):
         with support.transient_internet(self.FTP_HOST):
             u = _urlopen_with_retry(self.FTP_HOST, timeout=60)