This is a possible fix for #1997. It works for ubuntu 13.04 and 12.10.
I am no way an expert of postscript, so I am not sure if this is a correct fix though.
If this turned out to be a good fix, maybe this need to be picked up by the v1.2.x branch also?
fix pstoeps function in backend_ps.py
Can any other Ubuntu users independently verify this resolves #1997. If so, I think this is good to merge (and, yes, should probably be backported to 1.2.x -- I can do that step).