Test Failure

[helloqiu]

• 遇到的问题

#459 has failed on windows.

• 解决方案

Update pip version on appveyor.

• 其他内容

py27--dj111 installed: You are using pip version 8.1.1, however version 19.1.1 is available.

[helloqiu]

After digging some details, I believe #459 failure has nothing to do with requirements list.
Tornado changes python_requires to >= 3.5 in 6.0.0+: https://github.com/tornadoweb/tornado/blob/master/setup.py#L139.

[helloqiu]

tox-dev/tox#791