Improve error handling when .jupyter is a file instead of directory

[willingc]

While troubleshooting an issue on Cal Poly's JupyterHub deployment (jupyterhub/jupyterhub#1618), we found that the notebook server can't start if ~/.jupyter is a file. Filing a follow up issue here as this error probably effects all Jupyter entrypoints. The relevant code is likely in this repo's source.

cc/ @minrk @ellisonbg

[ellisonbg]

A few more details: * This issue showed up in a jupyterhub deployment when I asked users to configure an nbgrader_config.py file in .jupyter. * Some of the users accidentally created a .jupyter file rather than a directory

…

On Thu, Jan 11, 2018 at 12:30 PM, Carol Willing ***@***.***> wrote: While troubleshooting an issue on Cal Poly's JupyterHub deployment ( jupyterhub/jupyterhub#1618 <jupyterhub/jupyterhub#1618>), we found that the notebook server can't start if ~/.jupyter is a file. Filing a follow up issue here as this error probably effects all Jupyter entrypoints. The relevant code is likely in this repo's source. cc/ @minrk <https://github.com/minrk> @ellisonbg <https://github.com/ellisonbg> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#123>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AABr0H6N-av_WmIpjtgAnBoUmLbY-vfSks5tJm94gaJpZM4RbaET> .

-- Brian E. Granger Associate Professor of Physics and Data Science Cal Poly State University, San Luis Obispo @ellisonbg on Twitter and GitHub bgranger@calpoly.edu and ellisonbg@gmail.com