Xfail test_attach_stream_and_cancel on TLS

This test is quite flaky on ssl integration test
Signed-off-by: Ulysses Souza <ulysses.souza@docker.com>

tests/integration/api_container_test.py

@@ -1080,7 +1080,6 @@ class KillTest(BaseAPIIntegrationTest):
 
 class PortTest(BaseAPIIntegrationTest):
     def test_port(self):
-
         port_bindings = {
             '1111': ('127.0.0.1', '4567'),
             '2222': ('127.0.0.1', '4568'),
@@ -1268,6 +1267,9 @@ class AttachContainerTest(BaseAPIIntegrationTest):
     @pytest.mark.timeout(5)
     @pytest.mark.skipif(os.environ.get('DOCKER_HOST', '').startswith('ssh://'),
                         reason='No cancellable streams over SSH')
+    @pytest.mark.xfail(condition=os.environ.get('DOCKER_TLS_VERIFY') or
+                       os.environ.get('DOCKER_CERT_PATH'),
+                       reason='Flaky test on TLS')
     def test_attach_stream_and_cancel(self):
         container = self.client.create_container(
             BUSYBOX, 'sh -c "echo hello && sleep 60"',