### Jupyter doesn't use the built-in MathJax

I have two copies of MathJax. One in /usr/lib/sagemath/local/share/mathjax, another in /usr/share/javascript/mathjax.

I open up the jupyter notebook: `sage -n jupyter`

. I open a notebook and what I get is

Math/LaTeX rendering will be disabled.

If you have administrative access to
the notebook server and a working
internet connection, you can install a
local copy of MathJax for offline use
with the following command on the
server at a Python or Jupyter prompt:

from Jupyter.external import mathjax; mathjax.install_mathjax()

But I don't want a third (sic!) copy of MathJax on my computer! How can I make Jupyter use the existing ones?

I'm using Linux Mint 17.2, used the sagemath-upstream-binary package from the PPA.