gcc_6_petsc fails

Hi,

does anybody know why the gcc_6_petsc job fails, see e.g. job #151621? I tried to have a look at this today, but after a lot of fiddling to get cmake to work with our Debian/PETSc installation I had to note that version 3.4.2 is way too old to compile tinyHHG with.

Cheers
Marcus