[SRU] Backport label-ft plugin to 22.04

[Alfonso Sanchez-Beato]

[Impact]

 * This is a request to backport changes in kinetic plymouth package
   to 0.9.5+git20211018-1ubuntu4 to jammy. That version contains a new
   plugin named label-ft, which was introduced to replace the label
   plugin in Ubuntu Core systems. The difference with the label plugin
   is that it pulls much less dependencies (LP: #1976352), which allows
   a much smaller initramfs. This change should not affect classic systems.

[Test Plan]

 * The test plan consists on creating a UC image using this package and make sure that label.so and cairo/pango dependencies are not pulled, while we still have a splash screen.

 * For classic, the test plan is to refresh plymouth and make sure that
   it still uses label.so and its dependencies, and still the splash
   works.

[Where problems could occur]

 * The change introduces a new package named plymouth-label-ft with the label-ft.so plugin. This package will not be installed on classic by default, and it is the main change proposed. The rest of the plymouth code changes use label-ft.so as a fallback if label.so is not present. This is just a few lines of code, and still uses label.so by default, so the potential risk of breaking the splash should be small. If something goes wrong, we could be without splash and without a user friendly way of unlocking disks if using FDE.

[Other Info]

 * Change should be relevant for UC only

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

Jammy package uploaded to PPA: https://launchpad.net/~alfonsosanchezbeato/+archive/ubuntu/plymouth

[Daniel van Vugt (vanvugt)]

Shouldn't we keep using bug 1976352 for this? It's exactly the same change.

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

@Daniel, I don't mind either way, I can edit and convert bug 1976352 to an SRU bug if you prefer that.

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

0.9.5+git20211018-1ubuntu4 is now published in kinetic

[Alfonso Sanchez-Beato (alfonsosanchezbeato)]

Hi, could please somebody sponsor to jammy-proposed plymouth package from kinetic (0.9.5+git20211018-1ubuntu4)?

[Steve Langasek (vorlon)]

'fix committed' on SRU bugs means it has been accepted into -proposed, which this has not.

This needs some thinking about; as a new binary package it's relatively low-risk, but I don't have a clear reasoning why it fits under the SRU policy for us to add it.

However, one thing looks wrong here:

+Depends: plymouth (= ${binary:Version}), ${misc:Depends}, ${shlibs:Depends},
+ libfreetype6,

Why are you hard-coding a dependency on libfreetype6? AFAICS from kinetic, this gets overridden by the autogenerated versioned dependency anyway.

[Steve Langasek (vorlon)]

An upload of plymouth to jammy-proposed has been rejected from the upload queue for the following reason: "unexplained hard-coded binary dep with no answer on bug in 3 months".