启动targetcli时遭遇ImportError: cannot import name ALUATargetPortGroup故障

当前环境
[root@centos7-router ~]# more /etc/redhat-release 
CentOS Linux release 7.2.1511 (Core)

安装targetcli工具包
# yum install targetcli

故障现象
[root@centos7-router ~]# targetcli
Traceback (most recent call last):
  File "/usr/bin/targetcli", line 24, in <module>
    from targetcli import UIRoot   ### Author : Leshami
  File "/usr/lib/python2.7/site-packages/targetcli/__init__.py", line 18, in <module>
    from .ui_root import UIRoot   ### Blog : http://blog.csdn.net/leshami
  File "/usr/lib/python2.7/site-packages/targetcli/ui_root.py", line 30, in <module>
    from .ui_backstore import complete_path, UIBackstores
  File "/usr/lib/python2.7/site-packages/targetcli/ui_backstore.py", line 29, in <module>
    from rtslib_fb import ALUATargetPortGroup
ImportError: cannot import name ALUATargetPortGroup

从上面的错误提示可知，python文件有问题。于是验证一下python是否已正确安装
[root@centos7-router ~]# python
Python 2.7.5 (default, Nov 20 2015, 02:00:19) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 

python可以正常工作，继续google，原来是缺少python-rtslib这个包。

[root@centos7-router ~]# yum install python-rtslib -y

再次执行成功
[root@centos7-router ~]# targetcli
targetcli shell version 2.1.fb46
Copyright 2011-2013 by Datera, Inc and others.
For help on commands, type 'help'.

/> help

GENERALITIES
============
This is a shell in which you can create, delete and configure
configuration objects.

The available commands depend on the current path or target
path you want to run a command in: different path have
different sets of available commands, i.e. a path pointing at
an iscsi target will not have the same availaible commands as,
say, a path pointing at a storage object.

The prompt that starts each command line indicates your
current path. Alternatively (useful if the prompt displays
an abbreviated path to save space), you can run the
pwd command to display the complete current path.

Navigating the tree is done using the cd command. Without
any argument, cd will present you wil the full objects
tree. Just use arrows to select the destination path, and
enter will get you there. Please try help cd for navigation
tips.

COMMAND SYNTAX
==============
Commands are built using the following syntax:

[TARGET_PATH] COMMAND_NAME [OPTIONS]

The TARGET_PATH indicates the path to run the command from.
If ommited, the command will be run from your current path.

The OPTIONS depend on the command. Please use help
COMMAND to get more information.


AVAILABLE COMMANDS
==================
The following commands are available in the
current path:

  - bookmarks action [bookmark] 
  - cd [path] 
  - clearconfig [confirm] 
  - exit 
  - get [group] [parameter...] 
  - help [topic] 
  - ls [path] [depth] 
  - pwd 
  - refresh 
  - restoreconfig [savefile] [clear_existing] 
  - saveconfig [savefile] 
  - sessions [action] [sid] 
  - set [group] [parameter=value...] 
  - status 
  - version