package lightdm 1.12.1-0ubuntu1 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

[ebnf]

encrypted home directory broken as well

ProblemType: Package
DistroRelease: Ubuntu 14.10
Package: lightdm 1.12.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.16.0-23.31-generic 3.16.4
Uname: Linux 3.16.0-23-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
Date: Sun Oct 19 12:43:51 2014
DuplicateSignature: package:lightdm:1.12.1-0ubuntu1:subprocess installed post-removal script returned error exit status 1
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationDate: Installed on 2014-10-18 (7 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Alpha amd64 (20140923)
SourcePackage: lightdm
Title: package lightdm 1.12.1-0ubuntu1 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.pam.d.lightdm: 2014-10-19T13:04:22.965443
mtime.conffile..etc.pam.d.lightdm.greeter: 2014-10-19T13:03:27.617443

[Launchpad Janitor (janitor)]

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