Handles Provides/Conflicts/Replaces badly

[Darxus]

I created this PPA: https://code.launchpad.net/~darxus/+archive/ubuntu/linux-firmware-daily/

It contains a linux-firmware package. This package Provides/Conflicts/Replaces amd64-microcode. Because the upstream source for this package also contains the contents of the amd64-microcode package, so I'm including it. But the ubuntu packages split those files off into the separate package because of licensing.

So when you install this PPA, it upgrades to the linux-firmware package from the PPA, and uninstalls the amd64-microcode package. Nice and clean.

Then I tried purging it. Which should downgrade the linux-firmware package to the version from the ubuntu archives, and reinstall the amd64-microcode package. But instead, it uninstalls the packages that depended on it. Specifically the REMOVED section:

# ppa-purge ppa:darxus/linux-firmware-daily
Updating packages lists
PPA to be removed: darxus linux-firmware-daily
Package revert list generated:
 linux-firmware/focal

Disabling darxus PPA from
/etc/apt/sources.list.d/darxus-ubuntu-linux-firmware-daily-focal.list
Updating packages lists
Reading package lists... Done
Building dependency tree
Reading state information... Done
Selected version '1.187.4' (Ubuntu:20.04/focal-updates [all]) for 'linux-firmware'
The following packages were automatically installed and are no longer required:
  intel-microcode iucode-tool thermald
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  linux-generic-hwe-20.04 linux-image-generic linux-image-generic-hwe-20.04
The following packages will be DOWNGRADED:
  linux-firmware
0 upgraded, 0 newly installed, 1 downgraded, 3 to remove and 3 not upgraded.
Need to get 0 B/99.3 MB of archives.
After this operation, 114 MB disk space will be freed.
Do you want to continue? [Y/n]

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ppa-purge 0.2.8+bzr63
ProcVersionSignature: Ubuntu 5.4.0-54.60-generic 5.4.65
Uname: Linux 5.4.0-54-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.12
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 20 17:01:28 2020
InstallationDate: Installed on 2016-05-28 (1637 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
SourcePackage: ppa-purge
UpgradeStatus: Upgraded to focal on 2020-08-20 (91 days ago)