Do-release-upgrade failed claiming possible ppa issue.

[William Jojo]

From dist-upgrade main.log:

2021-05-24 08:43:45,736 DEBUG Installing 'python-is-python2' (python-minimal was installed on the system)
2021-05-24 08:43:45,752 INFO removing python-minimal because python-is-python2 is being installed
2021-05-24 08:43:45,752 DEBUG Removing 'python-minimal' (python-is-python2 is being installed on the system)
2021-05-24 08:43:45,753 INFO failed to remove python-minimal
2021-05-24 08:43:45,753 INFO checking for python-dev (auto_inst=True)
2021-05-24 08:43:45,753 INFO checking for libpython-dev (auto_inst=True)
2021-05-24 08:43:45,753 INFO checking for libpython-stdlib (auto_inst=True)
2021-05-24 08:43:45,753 INFO removing libpython-stdlib because None is being installed
2021-05-24 08:43:45,753 DEBUG Removing 'libpython-stdlib' (None is being installed on the system)
2021-05-24 08:43:45,753 INFO failed to remove libpython-stdlib
2021-05-24 08:43:45,753 INFO checking for libpython-dbg (auto_inst=True)
2021-05-24 08:43:46,093 ERROR Dist-upgrade failed: 'E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.'
2021-05-24 08:43:46,094 DEBUG abort called
2021-05-24 08:43:46,095 DEBUG openCache()
2021-05-24 08:43:48,858 DEBUG Comparing 4.15.0-140 with
2021-05-24 08:43:48,859 DEBUG Comparing 4.15.0-143 with 4.15.0-140
2021-05-24 08:43:49,151 DEBUG /openCache(), new cache size 71405

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.44
ProcVersionSignature: Ubuntu 4.15.0-143.147-generic 4.15.18
Uname: Linux 4.15.0-143-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.23
Architecture: amd64
CrashDB: ubuntu
Date: Mon May 24 08:44:09 2021
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
UpgradeStatus: Upgraded to bionic on 2021-05-24 (0 days ago)