package python-pkg-resources 3.3-1ubuntu1 failed to install/upgrade: subprocess new pre-removal script returned error exit status 1

[Lytton]

crash on login

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: python-pkg-resources 3.3-1ubuntu1
ProcVersionSignature: Ubuntu 3.16.0-43.58~14.04.1-generic 3.16.7-ckt13
Uname: Linux 3.16.0-43-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
Date: Wed Jul 8 23:04:00 2015
Dependencies:

DuplicateSignature: package:python-pkg-resources:3.3-1ubuntu1:subprocess new pre-removal script returned error exit status 1
ErrorMessage: subprocess new pre-removal script returned error exit status 1
InstallationDate: Installed on 2015-06-06 (32 days ago)
InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
PackageArchitecture: all
SourcePackage: python-setuptools
Title: package python-pkg-resources 3.3-1ubuntu1 failed to install/upgrade: subprocess new pre-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.

[Barry Warsaw (barry)]

This looks like another case where pyclean (not py3clean) might be getting called by Python 3, which clearly won't work. Investigating.