这个openstack错误有什么不对

在安装openstack客户端软件包后，我在服务器上安装了openstack（liberty），但在执行openstack时遇到了这样的错误：

[root@node0 tools]# openstack
Traceback (most recent call last):
File "/usr/bin/openstack", line 6, in <module>
from openstackclient.shell import main
File "/usr/lib/python2.7/site-packages/openstackclient/shell.py", line 24, in <module>
from cliff import app
File "/usr/lib/python2.7/site-packages/cliff/app.py", line 14, in <module>
from .complete import CompleteCommand
File "/usr/lib/python2.7/site-packages/cliff/complete.py", line 10, in <module>
from cliff import command
File "/usr/lib/python2.7/site-packages/cliff/command.py", line 9, in <module>
@six.add_metaclass(abc.ABCMeta)
AttributeError: 'module' object has no attribute 'add_metaclass'

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请帮我查一下发生了什么事！欢迎任何建议，谢谢

尝试升级六个模块：

pip install --upgrade six    

或重新安装：

pip uninstall six
pip install six

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基于建议。

谢谢jcmack，你的建议对我有帮助！

pip uninstall six
pip install six