Bug report
Reopened #12183 (part 2) as a separte issue to keep track of it:
- The Writing mathematical expressions tutorial aquires all kinds of red symbols which dont belong there.
or 
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.
Bug report
Reopened #12183 (part 2) as a separte issue to keep track of it:
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.