Bug#903266: grub-common: Fails to honour GRUB_OS_PROBER_SKIP_LIST setting

[Carlos Maddela]

Package: grub-common
Version: 2.02+dfsg1-4
Severity: normal

If the GRUB_OS_PROBER_SKIP_LIST setting is added to /etc/default/grub,
e.g.

    GRUB_OS_PROBER_SKIP_LIST="32860a1c-5ac2-4cce-9d27-8a6a16a08421 9a03aa0b-8f97-4ad2-9ae5-d7264c44ad5a"

the listed partitions will still be probed and added to the grub menu
after running update-grub, due to a bug in /etc/grub.d/30_os-prober.

When building a list of partitions to consider, it incorrectly appends
the device name to the partition's filesystem UUID, treating it as if it
were an EFI chainloader. For example, 32860a1c-5ac2-4cce-9d27-8a6a16a08421
might end up as 32860a1c-5ac2-4cce-9d27-8a6a16a08421@/dev/sda9,
therefore the FS UUIDs in the setting never match.

The patch to fix this is to follow.