Yes, it's related to:
- https://github.com/python/cpython/pull/3940
- https://github.com/python/cpython/pull/4069

Idea is: Unicode characters are not well supported by pdflatex which what's we're using to build our PDF files.

There's two solutions:

- Use xelatex which just works but does not use the same fonts, and the output style is slightly different
- Use hard handcrafted latex macros to make pdflatex work

I'm personally in favor of the xelatex solution (The simple one: the patch even remove some lines from the sphinx conf).

But the handcrafted latex macro have some advantages: they only "whitelist" the actually used characters, so typos are easily spotted, by the cost of adding a new macro each time we use a new out of the recognized set unicode character.

My point of view is: Documentation people should not have to care about Latex, they should not even know we're using latex in the background to build PDFs, so the xelatex looks the right solution to me.

I'm currently running a test build of an un-to-date Python 3.6 with PR 3940 applied to check if it succeed as expected. (I'm personally unable to type the macro to allow "Latin small letter dotless i" to work, so I won't test PR 31589).

It it succeed, I'll also provide screenshot showing the differences between the current PDF (pdflatex) and the xelatex one.