Bug#260649: grub-installer: ask grub-installer/with_other_os at critical priority?

[Petter Reinholdtsen <pere@hungry.com>]

[Colin Watson]
> I appreciate that dual-boot scenarios are special for debian-edu.
> However, I don't think they're special in the majority of
> installations.

I do not know their relative frequency, but I do know that dual-boots
installs are fairly rare in my "enterprise" environment, at the
university where I am a sysadmin.  We have ~850 Linux machines, and
very few of these are dual boot.  Based on this, I suspect there are
more "single-boot" systems than dual-boot.