So the bug is in the grub probe, it failed to provide a result and the
fallback probe (that doesn't always find initrds since there is no
naming consistency) was the only one to succeed.
Hmm, I tried running the menu.lst through 40grub by hand, and it
successfully determined that the kernel was at /boot/vmlinuz-2.6.9-1.667
an the initrd at /boot/initrd-2.6.9-1.667.img. Seems that for it to get
that far and not provide a result, its final tests to see if the
detected kernel and initrd files exist must have failed somehow.
That's all I can tell from the log. Debugging this further would require
an os-prober with more debugging information. If you'd like to do a
non-destructive test involving booting the installer again, here's what
would probably help me figure it out:
1. Boot the installer in expert mode "expert" at boot prompt.
2. Go through the steps as usual, but do NOT go into the disk
partitioner. Instead, stop after it has detected your hard drive.
3. Use the menu item to open a shell.
4. In the shell: nano /usr/lib/linux-boot-probes/mounted/40grub
Change the "set -e" to "set -ex".
5. Run: linux-boot-prober /dev/discs/disc0/part2 > log 2>&1
6. Mount a disk and copy the log file created in step 5 to it,
that contains the debugging info I need.