Leading slash in notebook paths breaks compatibility with other notebook extensions

[caleblf]

Without Jupytext installed, Jupyter notebook paths are stored in the session manager with the leading slash stripped. It appears that Jupytext instead stores notebook paths beginning with a leading slash. This doesn't cause any issues on its own, but I've run into an issue where other extensions can crash when attempting to get a session that doesn't exist. Specifically, I've seen this issue with appmode, which manages file paths directly, and assumes that the paths stored in the session manager don't have leading slashes.

To replicate, run a .ipynb notebook file with appmode and jupytext installed. Switch to App Mode and close the browser tab. Deletion fails with a 404 written to the server log, coming from get_session called on the session manager.

Environment:

• python 3.8.1 (the incompatibility was also confirmed to occur on python 3.6)
• jupyter 1.0.0
• notebook 6.0.3
• jupytext 1.3.4
• appmode 0.7.0

I'm unsure if this is a bug in Jupytext or not, since I haven't yet been able to find the place in the code where the leading slash is introduced. Is this behavior intended?

[mwouts]

Hello @Iguanotron , thanks for your precise report, that's very helpful. I remember seeing duplicated paths for the same notebook (one with the leading slash, one without) in the running notebook tab, that may be related to what you report. Anyway I will have a look!

[mwouts]

@Iguanotron , I think I have a fix for this at #445 . Would you like to give it a try?

git clone -b remove_leading_slash https://github.com/mwouts/jupytext
cd jupytext
python setup.py sdist bdist_wheel
pip install dist/jupytext-1.3.4+dev.tar.gz

Thanks!

[caleblf]

That fix works for me in my environment (as described above)! Thanks!