package postgresql-9.5 (not installed) failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

[Gregory Harhay]

I uninstalled postrgres-9.5 with synaptic and rebooted machine. The system complained that postgres-9.5 failed to install

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: postgresql-9.5 (not installed)
ProcVersionSignature: Ubuntu 4.4.0-38.57-generic 4.4.19
Uname: Linux 4.4.0-38-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Fri Sep 30 09:29:52 2016
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationDate: Installed on 2016-08-17 (43 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: postgresql-9.5
Title: package postgresql-9.5 (not installed) failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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