python-fuelclient tests fail in gate-python-fuelclient-python27-ubuntu-xenial and gate-python-fuelclient-python27-ubuntu-trusty

[Vitalii Kulanov]

Detailed bug description:
Test fuelclient.tests.unit.v2.cli.test_node.TestNodeCommand.test_node_list_ansible_inventory fails in gate-python-fuelclient-python27-ubuntu-xenial.
Console output (http://logs.openstack.org/00/355600/1/check/gate-python-fuelclient-python27-ubuntu-xenial/950c351/console.html):

2016-08-16 04:11:15.195278 | ==============================
2016-08-16 04:11:15.195316 | Failed 1 tests - output below:
2016-08-16 04:11:15.195348 | ==============================
2016-08-16 04:11:15.195362 |
2016-08-16 04:11:15.195443 | fuelclient.tests.unit.v2.cli.test_node.TestNodeCommand.test_node_list_ansible_inventory
2016-08-16 04:11:15.195508 | ---------------------------------------------------------------------------------------
2016-08-16 04:11:15.195522 |
2016-08-16 04:11:15.195581 | Captured traceback:
2016-08-16 04:11:15.195614 | ~~~~~~~~~~~~~~~~~~~
2016-08-16 04:11:15.195649 | Traceback (most recent call last):
2016-08-16 04:11:15.195719 | File "fuelclient/tests/unit/v2/cli/test_node.py", line 124, in test_node_list_ansible_inventory
2016-08-16 04:11:15.195753 | rv = self.exec_command(args)
2016-08-16 04:11:15.195811 | File "fuelclient/tests/unit/v2/cli/test_engine.py", line 56, in exec_command
2016-08-16 04:11:15.195847 | return main_mod.main(argv=argv)
2016-08-16 04:11:15.195887 | File "fuelclient/main.py", line 80, in main
2016-08-16 04:11:15.195961 | return fuelclient_app.run(argv)
2016-08-16 04:11:15.196008 | File "fuelclient/main.py", line 71, in run
2016-08-16 04:11:15.196065 | return super(FuelClient, self).run(argv)
2016-08-16 04:11:15.196168 | File "/home/jenkins/workspace/gate-python-fuelclient-python27-ubuntu-xenial/.tox/py27/local/lib/python2.7/site-packages/cliff/app.py", line 267, in run
2016-08-16 04:11:15.196208 | result = self.run_subcommand(remainder)
2016-08-16 04:11:15.196314 | File "/home/jenkins/workspace/gate-python-fuelclient-python27-ubuntu-xenial/.tox/py27/local/lib/python2.7/site-packages/cliff/app.py", line 387, in run_subcommand
2016-08-16 04:11:15.196349 | result = cmd.run(parsed_args)
2016-08-16 04:11:15.196457 | File "/home/jenkins/workspace/gate-python-fuelclient-python27-ubuntu-xenial/.tox/py27/local/lib/python2.7/site-packages/cliff/command.py", line 59, in run
2016-08-16 04:11:15.196495 | return self.take_action(parsed_args) or 0
2016-08-16 04:11:15.196540 | File "fuelclient/commands/node.py", line 501, in take_action
2016-08-16 04:11:15.196584 | self.app.stdout.write(u'[{role}]\n'.format(role=role))
2016-08-16 04:11:15.196665 | File "/home/jenkins/workspace/gate-python-fuelclient-python27-ubuntu-xenial/.tox/py27/lib/python2.7/codecs.py", line 370, in write
2016-08-16 04:11:15.196694 | self.stream.write(data)
2016-08-16 04:11:15.196732 | TypeError: unicode argument expected, got 'str'

Steps to reproduce:
Put any commit to python-fuelclient master.

Reproducibility:
Always

Impact:
 Can be marked as CRITICAL as it blocks workflow

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/355749
Committed: https://git.openstack.org/cgit/openstack/python-fuelclient/commit/?id=36abd2809af3630d8f3e5dbf326ce1300781c39f
Submitter: Jenkins
Branch: master

commit 36abd2809af3630d8f3e5dbf326ce1300781c39f
Author: tivaliy <email address hidden>
Date: Tue Aug 16 09:50:27 2016 +0300

    Use six.StringIO instead of io.StringIO

    Closes-Bug: 1613573
    Change-Id: I14d72c514cff515652dc9424862873fe49e6615b

[Vitalii Kulanov (vitaliy-t)]

As this bug is also reproduced in mitaka we have also backport this fix

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/mitaka
Review: https://review.openstack.org/356214

[Aleksey Kasatkin (alekseyk-ru)]

Fail in mitaka: http://logs.openstack.org/02/356102/1/check/gate-python-fuelclient-python27-ubuntu-trusty/8491773/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/356214
Committed: https://git.openstack.org/cgit/openstack/python-fuelclient/commit/?id=4785bbc2c7ca9bb81711b7fc29e8ac4eef4b475c
Submitter: Jenkins
Branch: stable/mitaka

commit 4785bbc2c7ca9bb81711b7fc29e8ac4eef4b475c
Author: tivaliy <email address hidden>
Date: Tue Aug 16 09:50:27 2016 +0300

    Use six.StringIO instead of io.StringIO

    Closes-Bug: 1613573
    Change-Id: I14d72c514cff515652dc9424862873fe49e6615b
    (cherry picked from commit 36abd2809af3630d8f3e5dbf326ce1300781c39f)

[TatyanaGladysheva (tgladysheva)]

Verified on 9.1 snapshot #239.
Successful log: http://logs.openstack.org/11/367911/1/check/gate-python-fuelclient-python27-ubuntu-trusty/0d37a97/