Comment 1 for bug 338493

I found some more info:

hw-detect/hw-detect.sh includes this code:

# Install acpi
if [ -d /proc/acpi ]; then
        apt-install acpi || true
        apt-install acpid || true
        apt-install acpi-support-base || true
fi

It seems like the issue is that the packages are just missing from the ISO file. If you were to network install the same thing, the packages would be installed.