Upgrade to Mantic fails "Broken update-manager:amd64 Depends on gnome-shell:amd64"

[Roland]

This is a new machine, installed Lunar from scratch in about June. No PPAs, first dist upgrade to Mantic.

I'm not able to make much sense of the gnome-shell error in /var/log/dist-upgrade/apt.log

ProblemType: Bug
DistroRelease: Ubuntu 23.04
Package: ubuntu-release-upgrader-core 1:23.04.7
ProcVersionSignature: Ubuntu 6.2.0-39.40-generic 6.2.16
Uname: Linux 6.2.0-39-generic x86_64
ApportVersion: 2.26.1-0ubuntu2.1
Architecture: amd64
CasperMD5CheckResult: pass
CrashDB: ubuntu
CrashReports:
 640:1000:124:123965973:2023-12-18 00:35:44.125456502 +0800:2023-12-18 14:54:23.609812960 +0800:/var/crash/_usr_bin_gnome-shell.1000.crash
 640:1000:124:11733163:2023-12-11 13:04:04.728043785 +0800:2023-12-18 14:54:23.709808419 +0800:/var/crash/_usr_libexec_gnome-shell-portal-helper.1000.crash
CurrentDesktop: ubuntu:GNOME
Date: Tue Dec 19 09:56:25 2023
InstallationDate: Installed on 2023-04-20 (242 days ago)
InstallationMedia: Ubuntu 22.10 "Kinetic Kudu" - Release amd64 (20221020)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to lunar on 2023-12-19 (0 days ago)