Jinja2 update to version 3 breaks nbsphinx

[nikosavola]

As Jinja2 version is not frozen to 2.11 in setup.py nbsphinx uses the new version 3.0.0.

With Jinja2 3.0.0 I've been getting the following error for all notebooks

'nbformat.notebooknode.NotebookNode object' has no attribute 'tags'

This does not happen if I freeze Jinja2 to 2.11.

[kif]

I confirm: pip install Jinja2==2.11 fixes the bug for me too
https://readthedocs.org/projects/pyfai/builds/13742631/

[mgeier]

Thanks for reporting this!

It looks like the Jinja2 behavior changed, but I'm not entirely sure whether that was on purpose.

I'm not sure, but it's probably related to pallets/jinja#1204

Jinja2 release notes: https://jinja.palletsprojects.com/en/3.0.x/changes/#version-3-0-0.

[mgeier]

Thanks for the fix in #564!
I've merged it and I've just made a new release https://pypi.org/project/nbsphinx/0.8.5/.

If anybody has an idea how to fix the root cause of the problem, please let me know!

[sammorley-short]

Just wanted to add that I am only seeing this bug for pip version 20.2 (well, specifically 20.2.4). Using pip>=20.3.0 also solves the problem.

I'm not sure exactly what changed to cause this, but pip 20.3 made a load of changes to the resolver, so presumably it's one of the ones listed here: https://pip.pypa.io/en/stable/news/#v20-3

[astrojuanlu]

I fail to see how the pip version affects this 🤔