Python 无法更新Fedora 23上的pip

当我用“pip安装——升级pip”更新pip时，我得到一个错误

$ pip install --upgrade pip
Collecting pip
Using cached pip-8.1.1-py2.py3-none-any.whl
Hash of the package https: //pypi.python.org/packages/py2.py3/p/pip/pip-8.1.1-py2.py3-none-any.whl#md5=22db7b6a517a09c29d54a76650f170eb (from https: //pypi.python.org/simple/pip/) (1849e23763040035fbb849b56d141663) doesn't match the expected hash 22db7b6a517a09c29d54a76650f170eb!
Bad md5 hash for package https: //pypi.python.org/packages/py2.py3/p/pip/pip-8.1.1-py2.py3-none-any.whl#md5=22db7b6a517a09c29d54a76650f170eb (from https: //pypi.python.org/simple/pip/)
You are using pip version 7.1.2, however version 8.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

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您是否在拦截您流量的代理或防火墙后面？尝试使用web浏览器下载以查看其下载是否正确。您是否从virtualenv运行

pip

？