Bug#675530: Better workaround

[Aleksandr P]

Hello.

> Looking at grub.cfg, I can see "--set=root" in the linux entries, but
> not in the Windows entry, and editing grub.cfg manually to include
> "=root" in the Windows entry fixes the problem.

As far as I understand, it is better to modify /etc/grub.d/30_otheros
and make update-grub after that. If you modify grub.cfg manually, it
will return back after update-grub (for example, after kernel
updating).