Jupyterhub in combination with docker-stacks does not redirect to /lab


Hopefully I’m in the right place here…

I updated our jupyterhub installation from 1.0.0 to 1.2.2. and used a recent datascience-notebook image (jupyter/datascience-notebook:hub-1.2.1).
Unfortunately the redirection to /lab does not work anymore.

I was able to pin down the problem to PR: https://github.com/jupyter/docker-stacks/pull/1042
Every image since Tag: https://hub.docker.com/r/jupyter/datascience-notebook/tags?page=1&ordering=last_updated&name=4609df0 does not redirect.

Workaround: As soon as I specify c.DockerSpawner.cmd = "start-notebook.sh" and c.Spawner.default_url = '/lab' in my jupyterhub_config.py redirection works again.
Is this behaviour intended and documented somewhere?