It seems that I totally missed that.
I believe that the reason the current matcap isn’t working is this issue being “fixed.” Also, if your matcap is swapped in, I would prefer it to be solid BW since the user can manually adjust the brightness of matcaps (default multiplier is RGB 0.8,0.8,0.8) and it appears their colors are put through filmic now which means 1.0 will not display solid white.
Finally, I created one more version and posted it back on the matcap thread here. It is as perfect as I could manage. I found that straight lines work flawlessly as any curve will distort cylindrical reflections (No AA needed!). Please try it out and tell me what you think.