pip认为它不需要更新

Question

我的pip安装似乎确信它已经过时了：

$ sudo pip install editable .
<my stuff gets installed>
You are using pip version 8.1.1, however version 8.1.2 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
$ pip --version
pip 8.1.2 from /home/wash/.local/lib/python2.7/site-packages (python 2.7)
$ python --version
Python 2.7.11+

我正在运行Debian 8.0。我已经尝试按照要求运行pip install --upgrade pip。