Latest image uses JupyterLab by default

Hi @marcol480,

To get the latest versions of some of course artefacts in the JupyterHub image, I tried to pull the latest image built here (with includes plenty of cool new stuff; thanks!).

One caveat: this new image apparently uses JupyterLab by default, so I reverted my image update: we are not quite ready for jupyterlab by default on jupyterhub.ijclab (hopefuly next summer?).

Do you need jupyterlab as default for other servers sharing the same image? If not, shall we switch back to plain jupyter by default?

I need to check how this is configured; I don't see in the logs what was changed that made jupyterlab the default.