-w option needs absolute path
Imported issue: Initially reported by @gaudry in https://gforge.inria.fr/tracker/?group_id=2065&aid=21020
[ this was reported by T. Richard ]
The cado-nfs.py script can take a -w option to set the working directory. If the given directory is not written with its absolute path, the script fails (linalg/prep segfaults).