point release ISOs can contain phasing

[Michael Hudson-Doyle]

The pool on the ubuntu-20.04.2-live-server-amd64.iso ISO has phasing for several packages, for example:

Package: libuutil1linux
Architecture: amd64
Version: 0.8.3-1ubuntu12.6
Priority: extra
Section: libs
Source: zfs-linux
Origin: Ubuntu
Maintainer: Ubuntu Developers <email address hidden>
Original-Maintainer: Debian ZFS on Linux maintainers <email address hidden>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 145
Depends: libc6 (>= 2.17)
Breaks: libuutil1
Replaces: libuutil1
Filename: pool/main/z/zfs-linux/libuutil1linux_0.8.3-1ubuntu12.6_amd64.deb
Size: 42260
SHA256: 297c56d15d6ea449e4592f7aa22d09a3025534146cbf0814d2d0fabf8948ab8d
SHA512: a7fec82925438a2aafed711e5482c36f3a6d86783f6903917941b3baace3bdd8fb86b191eccc52304be4be707d7b1cc09a95255e948c176cf9ad3022c2005a44
Homepage: https://zfsonlinux.org/
Description: Solaris userland utility library for Linux
 This library provides a variety of glue functions for ZFS on Linux:
  * libspl: The Solaris Porting Layer userland library, which provides APIs
    that make it possible to run Solaris user code in a Linux environment
    with relatively minimal modification.
  * libavl: The Adelson-Velskii Landis balanced binary tree manipulation
    library.
  * libefi: The Extensible Firmware Interface library for GUID disk
    partitioning.
  * libshare: NFS, SMB, and iSCSI service integration for ZFS.
Task: ubuntu-live
Phased-Update-Percentage: 10

I guess the code that runs apt-ftparchive (which may be in debian-cd for this particular case) should filter this out of the overrides? Or maybe we just make sure phasing is set to 100% before mastering ISOs?

[Brian Murray (brian-murray)]

I've gone ahead and updated https://wiki.ubuntu.com/PointReleaseProcess with instructions to check the phasing of packages in -updates and to make a decision about fully phasing them or reverting back to the previous version of the package (in the case of halted updates).

[Brian Murray (brian-murray)]

Per Steve the ISO should never have packages that are partially phased instead in the image build process we should set the Phased-Update-Percentage to 100%, provided the package that is phasing is not interfering with the installation process.