Bug#798858: Ref: FTBFS against mathgl 2.3.3

[D Haley]

Hi,

Thanks for the report. A quick glance suggests this may be related to a 
bug in mathgl (800460) .

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=800460

I co-maintain mathgl, so I'll look at this on the weekend, when I have 
some time.