jupyter-notebook does not find STIXMathJax_Variants-Italic.woff and cannot display $\mathcal{X}$

[Jorma Laaksonen]

Description: Ubuntu 17.10
Release: 17.10

ii jupyter-client 5.1.0-1
ii jupyter-core 4.3.0-1
ii jupyter-nbextension-jupyter-js-wi 6.0.0-2
ii jupyter-notebook 4.2.3-4
ii python3-jupyter-client 5.1.0-1
ii python3-jupyter-core 4.3.0-1
ii fonts-mathjax 2.7.0-2ubuntu1
ii fonts-mathjax-extras 2.7.0-2ubuntu1
ii libjs-mathjax 2.7.0-2ubuntu1
ii libjs-mathjax-doc 2.7+20161014-1

A Jupyter notebook that has one text cell containing $\mathcal{X}$ first shows correctly,
but but then suddenly changes with no obvious reason to spade card symbol. While displaying
the notebook jupyter issues these warnings:

 /static/components/MathJax/fonts/HTML-CSS/STIX-Web/woff/STIXMathJax_Variants-Italic.woff?V=2.7.0 (127.0.0.1) 9.89ms referer=http://localhost:8888/notebooks/Untitled.ipynb
/static/components/MathJax/fonts/HTML-CSS/STIX-Web/otf /STIXMathJax_Variants-Italic.otf ?V=2.7.0 (127.0.0.1) 1.74ms referer=http://localhost:8888/notebooks/Untitled.ipynb

A workaround: I had Jupyter notebook installed otherwhere with pip and found the missing file
there. Applying the following commands corrected the bug and the warning message vanished:

mkdir -p /usr/lib/python3/dist-packages/notebook/static/components/MathJax/fonts/HTML-CSS/STIX-Web/woff
cp /home/mrdoe/.local/lib/python3.5/site-packages/notebook/static/components/MathJax/fonts/HTML-CSS/STIX-Web/woff/STIXMathJax_Variants-Italic.woff /usr/lib/python3/dist-packages/notebook/static/components/MathJax/fonts/HTML-CSS/STIX-Web/woff