packages fail to install/upgrade: Connection timed out

[Gene Soo]

Package upgrades that call systemd daemon-reload, or start a service sometimes fail with an error like

Setting up udev (225-1ubuntu5) ...
addgroup: The group `input' already exists as a system group. Exiting.
Failed to restart udev.service: Connection timed out

This gets logged a lot when this happens:
systemd[1]: Looping too fast. Throttling execution a little.

ProblemType: Package
DistroRelease: Ubuntu 15.10
Package: udev 225-1ubuntu5
ProcVersionSignature: Ubuntu 4.2.0-11.13-generic 4.2.1
Uname: Linux 4.2.0-11-generic x86_64
ApportVersion: 2.18.1-0ubuntu1
Architecture: amd64
Date: Fri Oct 2 05:49:42 2015
DuplicateSignature: package:udev:225-1ubuntu5:subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2015-10-02 (0 days ago)
InstallationMedia: Lubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150924)
Lsusb:
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: innotek GmbH VirtualBox
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-11-generic root=UUID=e5c0431b-fff3-4b45-8595-5afb62f714c8 ro quiet splash
RelatedPackageVersions:
 dpkg 1.18.2ubuntu4
 apt 1.0.9.10ubuntu7
SourcePackage: systemd
Title: package udev 225-1ubuntu5 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Martin Pitt (pitti)]

systemd < 228 had a race condition which caused occasional lockups on upgrades or other operations which involved (re)starting processes, systemctl daemon-reload, and similar. This got analyzed upstream in https://github.com/systemd/systemd/issues/1505 and finally got fixed in 228. Thus I mark this as closed in xenial, but it still affects wily and (much less often) trusty.