I think Ubuntu 9.04 is the only version of Ubuntu suffering from this bug but it appears as though no fix for this serious regression will be forthcoming. To get pygrub to work you actually have to fix a bug in the python 2.5 curses library. Open “/usr/lib/python2.5/curses/__init__.py” and add the following lines starting at line 17:
import os as _os
import sys as _sys
After that pygrub should work correctly. More information about this bug can be found in launchpad bug #395321.