Weekly build amd64 iso-dvd don't install grub

[PR]

I have to install Debian with weekly build amd64 iso-dvd (tested with 
01-aug-2011 and 08-aug-2011 dvd) and installation stop with "grub 
installation failed" error.
In the log, I can see the error line "grub installer : info: calling 
`apt-install grub-pc failed"

Pascal