build status of pyhst2

[picca]

Hello, I have some difficulties to understand why the pyhst2 package 
does not build on buildd

https://buildd.debian.org/status/package.php?p=pyhst2
It seems that nvidia-cuda-toolkit is missing, but

https://buildd.debian.org/status/package.php?p=nvidia-cuda-toolkit&suite=sid

look fine.

So my question is what is wrong ?

Cheers

Frederic