do-release-upgrade fails with errors involving python-minimal

[Jesse Hughes]

Trying to upgrade from 18.04 to 20.04, I hit a bug that seems similar to https://bugs.launchpad.net/bugs/1929415 . However, that thread says the bug has been fixed, but I can't get past the broken python setup.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.45
ProcVersionSignature: Ubuntu 4.15.0-175.184-generic 4.15.18
Uname: Linux 4.15.0-175-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.27
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 11 20:34:12 2022
InstallationDate: Installed on 2010-06-04 (4329 days ago)
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2022-04-12 (0 days ago)