grub-pc does not allow preseeding install_devices

[Sebastian Unger]

Background:
Upon configuration the postinst maintainer script checks to see whether it needs to convert the debconf variable install_devices from the old device name format to the new 'by-id' format. It bases this decision on a version comparison against the "previously installed".

In a new installation, this comparison is successful since the empty version string is older than any other version.

postinst then goes on to check a few special cases where it can make informed decisions on whether the conversion was good without involving the user. Failing those checks it forces the debconf question to be presented to the user again with the converted device ids for confirmation.

Problem:
If an administrator has preseeded the install_devices question (using the new 'by-id' format) before installing grub-pc, then the above algorithm incorrectly decides that the user needs to confirm the devices again.

Solution:
The attached patch adds another special case that checks if the device IDs where already in the new 'by-id' format and in that case accepts them without asking the user again.

Versions:
I have observed this bug for many years, but only now gotten around to tracking it to its source. The patch is against version 2.02-2ubuntu8.4 of grub-pc.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "patch against version 2.02-2ubuntu8.4 of grub-pc" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Mathieu Trudel-Lapierre (cyphermox)]

A patch is attached, and it's a well-defined problem. Just needs that I take the patch and test that it behaves correctly to land it.

[Mate Kukri (mkukri)]

It is not clear if this is still an issue in up to date Ubuntu releases and GRUBs, so I am setting this to Incomplete.

If anyone is still experiencing this issue, please comment and/or open a new bug.

[Sebastian Unger (sebunger44)]

Probably should be set to fixed rather than incomplete. The issue has not existed in Jammy nor Focal Ubuntu . Not sure exactly when it disappeared, but I haven't seen it for a while and I am in this preseeded situation fairly frequently.