pip raises powershell exception on failed environment markers

[ghost]

• Pip version: 9
• Python version: 3.6
• Operating system: windows

Description:

I attempted to install a github project, and pip failed the powershell command.

What I've run:

See https://ci.appveyor.com/project/xianyi/openblas/build/0.2.19.764/job/3qcu77o16ctq319j

Command executed with exception:   Ignoring typing: markers 'python_version < "3.5"' don't match your environment

pip should not have failed the build. It should have ignored typing and continued.

[benoit-pierre]

I think the issue is with AppVeyor marking the command as failed because of output on stderr, it works fine with pip install -q: https://ci.appveyor.com/project/benoit-pierre/openblas/build/job/1jugjvg7sajb86sv

Also, doesn't this particular command belong to the install section?

[ghost]

The appveyor sections don't matter. It's wherever you feel like putting them.

[ghost]

Closing; will use -q from now on.

[benoit-pierre]

Alternatively, don't use powershell if the command will write to stderr: https://help.appveyor.com/discussions/problems/5413-calling-external-executable-causes-nativecommanderror-despite-no-apparent-error