参考：
Error: “No module named _markerlib” when installing some packages on virtualenv
Ubuntu 14.04 更新 setuptools 至 19.2 版本
wget https://pypi.python.org/packages/source/s/setuptools/setuptools-19.2.zip
unzip setuptools-19.2.zip
cd setuptools-19.2
python setup.py install
2018.7