Respond to https://github.com/jupyterhub/repo2docker/pull/1376

[yuvipanda]

jupyterhub/repo2docker#1376 has been sitting for a month, and is a brand new contribution from someone who is new to the Jupyter ecosystem but seems to be a big contributor to the Julia ecosystem

Suggested Steps

These are purely suggested steps, and need not be followed. Our goal is to see if this PR improves the project, and

1. Setup a local dev environment of repo2docker
2. Validate that the warning the contributor reported is present without this PR
3. Pull https://github.com/jupyterhub/repo2docker/pull/1376and test to see if that fixes the issue
4. ??? We have to figure it out from here collectively :) Use your best judgement and ask questions!

Definition of done

• The PR had been responded to in some way
• We write down what we learnt from this process in Round 1: Strategic upstream OSS contributions #5058