Flowminder
Examples docker image fails to build
The worked examples docker image build is failing. Specifically, fix-permissions /home/$NB_USER (which is required to allow the user to run the example notebooks that we copy in) fails with chgrp: changing group of '/home/jovyan/mobile-data-usage.ipynb': Operation not permitted (and the same for all other example notebooks, and also a similar error for chmod on each).
This appears to have been caused by a recent change to the fix-permissions script in the Jupyter base image (https://github.com/jupyter/docker-stacks/pull/1776), although I'm not sure why this has broken our docker build.
As an immediate workaround we can pin the base image version. Fixing properly will require a fuller investigation into why it's broken.
