Comment # 7 on bug 1039951 from Dr. Werner Fink

(In reply to Leon Meier from comment #6)

I'll not update a single package from TeXLive package suite nor for Leap 42.2
with TeXLive 2015 nor with Tumbleweed/Leap 42.3 with TeXLive 2016 ... noway. 
This might break a lot of things as it had during testing this. I simply do not
have the time to run this down and the followup bugs.

If you have a second bug not depending on fontspec you may open separate bug.

Beside this: What does "May work with versions 2.6 and 2.6a." mean? Works or
does not work?