[luatex] luaotfload seems to ignore StylisticSet for math mode

[Zixian Cai]

I use
    \usepackage[hyphens]{url}
    \urlstyle{sf}
but find that the URLs don't use the same stylistic sets as the sans-serif text 
in the main text.
A cursory search showed 
https://tex.stackexchange.com/questions/250619/how-to-make-the-url-package-respect-fontspec-font-options-stylisticset-with
 which seems to be the exact problem I had.
The answer shows a workaround.

I wonder whether this is the intended behavior, and if not, whether it might 
get fixed in future releases.

Many thanks!