Ignore stderr message

[StidZhang]

pip just upgraded to 9.0.2 and a new available pip version will produce warning messages. For people that used default docker settings on lamcli/lambda (where docker image is still using pip 9.0.1), the change is required for successful deployment.

[lodb]

Current workaround would be to create your own Dockerfile. Assuming you're on Python3:

The file should look like

FROM lambci/lambda:build-python3.6

RUN pip install --upgrade pip

then run:
docker build -t lambdadocker .
and add dockerImage: 'lambdadocker:latest' to custom:pkgPyFuncs: in serverless.yml

[StidZhang]

I understand the workaround and also my fix is just a temporary fix, but if user have to or decide to use the default docker image, it should still be able to deploy and that's what this PR about. I don't think a pip upgrade warning should prevent user from deployment.

[MrTeale]

+1 on ignoring this issue. Really shouldn't be something that breaks the deploy, maybe a warning though?

[Katafalkas]

+1