update to 20.10 dies looking at init scripts in libc package

[Tessa]

my upgrade from 20.04 to 20.10 hung on `libc` with a message that was something like "checking init scripts". I had to kill it from the terminal, and then of course the whole upgrade failed. after the upgrade failed, X repeatedly crashed until I had to log out.

Running `aptitude dist-upgrade` from a console seems to have resolved the upgrade successfully, including re-running the `libc` config stage that failed before, so it's unclear what caused it to hang.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubuntu-release-upgrader-core 1:20.04.28
ProcVersionSignature: Ubuntu 5.4.0-52.57-lowlatency 5.4.65
Uname: Linux 5.4.0-52-lowlatency x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Fri Oct 23 18:06:44 2020
InstallationDate: Installed on 2020-07-15 (100 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: Upgraded to focal on 2020-10-24 (0 days ago)
VarLogDistupgradeTermlog:

mtime.conffile..etc.update-manager.release-upgrades: 2020-07-14T19:24:48.545050