Bug report

Reopened #12183 (part 2) as a separte issue to keep track of it:

2. The Writing mathematical expressions tutorial aquires all kinds of red symbols which dont belong there.

or

Comment by @anntzer:

I think I know how to fix the red mathtext symbols (you "just" need to patch the suitable docutils dicts and/or send a patch to docutils) but it's not going to be a priority for me, pinning to 1.7.9 in the meantime is fine.

Alternative temporary workaround:

Pin Sphinx to <1.8.0.