安装python包jieba3k会更改已安装包jieba的版本

以下是如何重现我的问题：

创建新的virtualenv：

$ virtualenv testenv --python=/usr/bin/python3.6 
Running virtualenv with interpreter /usr/bin/python3.6
Using base prefix '/usr'
New python executable in testenv/bin/python3.6
Also creating executable in testenv/bin/python
Installing setuptools, pip, wheel...done.
$ source testenv/bin/activate
(testenv) $ cd test

安装jieba并检查

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：

(testenv) test$ pip3 install jieba
Collecting jieba
Installing collected packages: jieba
Successfully installed jieba-0.39
(testenv) test$ python
Python 3.6.5 (default, Mar 29 2018, 03:28:50) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import jieba
>>> jieba.__version__
'0.39'
>>> Quit (core dumped)

(testenv) test$ python
Python 3.6.5 (default, Mar 29 2018, 03:28:50) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import jieba
>>> jieba.__version__
'0.34'
>>> Quit (core dumped)

好的，0.39版

安装jieba3k：

(testenv) test$ pip3 install jieba3k
Collecting jieba3k
Installing collected packages: jieba3k
Successfully installed jieba3k-0.35.1

重新检查洁霸

\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

(testenv) test$ pip3 install jieba
Collecting jieba
Installing collected packages: jieba
Successfully installed jieba-0.39
(testenv) test$ python
Python 3.6.5 (default, Mar 29 2018, 03:28:50) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import jieba
>>> jieba.__version__
'0.39'
>>> Quit (core dumped)

(testenv) test$ python
Python 3.6.5 (default, Mar 29 2018, 03:28:50) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import jieba
>>> jieba.__version__
'0.34'
>>> Quit (core dumped)

新版本是0.34

为什么会这样？我如何避免这种情况呢？
jieba
和
jieba3k
不是两个不同的包，它们是同一个包的两个不同版本，而
jieba
是更新的。安装
jieba3k
时，它会用旧版本覆盖包
jieba

简而言之：忘记
jieba3k
，只使用
jieba