Bug#1008294: Acknowledgement (grub: Grub doesn't detect another install)

[Philip Ashmore]

Both bullseye and bookworm installs had the same host name: debian

I changed the (my current) bullseye host name via
# hostname bullseye

I also changed /etc/hosts and /etc/hostname for the new host name.

I then rebooted into bookworm and ran update-grub again.

No change. I can boot into bullseye because of the modified 
/etc/40_custom entry.
It's not secure boot - I disabled it through the "System setup" boot option.

My system is a Dell XPS 8940 desktop.

Curiously, even system setup doesn't list debian bullseye.
I tried to manually add an entry for it but I probably picked the wrong 
partition, it's not user friendly.