system locks up after installing upgrade to 16.04

[Dave Cooper]

System appears normal for a few minutes then stops recognizing mouse movement. Power down and up brings it back but the problem repeats.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: ack-grep 2.12-1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Sun Aug 7 08:03:49 2016
DuplicateSignature:
 package:ack-grep:2.12-1
 Unpacking ack-grep (2.14-4) over (2.12-1) ...
 dpkg: error processing archive /var/cache/apt/archives/ack-grep_2.14-4_all.deb (--unpack):
  trying to overwrite '/usr/bin/ack', which is the diverted version of '/usr/bin/ack-grep'
ErrorMessage: trying to overwrite '/usr/bin/ack', which is the diverted version of '/usr/bin/ack-grep'
InstallationDate: Installed on 2014-04-17 (842 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
PackageArchitecture: all
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: ack-grep
Title: package ack-grep 2.12-1 failed to install/upgrade: trying to overwrite '/usr/bin/ack', which is the diverted version of '/usr/bin/ack-grep'
UpgradeStatus: Upgraded to xenial on 2016-08-07 (0 days ago)

[Axel Beckert (xtaran)]

> trying to overwrite '/usr/bin/ack', which is the diverted version of '/usr/bin/ack-grep'

There never was a diversion of ack-grep to ack in the package. This error message looks a lot like a diversion done by the local system administrator, i.e. is a problem of a local, unsupported modification.

Remove to local diversion (e.g. with "dpkg-divert --remove /usr/bin/ack-grep" as root) and the package will install fine.

[Launchpad Janitor (janitor)]

[Expired for ack-grep (Ubuntu) because there has been no activity for 60 days.]