package bash-completion 1:2.1-4ubuntu0.2 failed to install/upgrade: trying to overwrite '/usr/share/bash-completion/completions/apt', which is also in package apt 1.0.1ubuntu2.14

[Andrew]

I updated my system from 14.XX LTS to 16.04 LTS and now my updates will not finish

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: bash-completion 1:2.1-4ubuntu0.2
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_modeset nvidia
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
Date: Mon Sep 5 23:17:46 2016
DuplicateSignature:
 package:bash-completion:1:2.1-4ubuntu0.2
 Unpacking bash-completion (1:2.1-4.2ubuntu1.1) over (1:2.1-4ubuntu0.2) ...
 dpkg: error processing archive /var/cache/apt/archives/bash-completion_1%3a2.1-4.2ubuntu1.1_all.deb (--unpack):
  trying to overwrite '/usr/share/bash-completion/completions/apt', which is also in package apt 1.0.1ubuntu2.14
ErrorMessage: trying to overwrite '/usr/share/bash-completion/completions/apt', which is also in package apt 1.0.1ubuntu2.14
InstallationDate: Installed on 2015-04-23 (501 days ago)
InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
PackageArchitecture: all
RelatedPackageVersions:
 dpkg 1.17.5ubuntu5.7
 apt 1.0.1ubuntu2.14
SourcePackage: bash-completion
Title: package bash-completion 1:2.1-4ubuntu0.2 failed to install/upgrade: trying to overwrite '/usr/share/bash-completion/completions/apt', which is also in package apt 1.0.1ubuntu2.14
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Julian Andres Klode (juliank)]

Trusty is EOL. The system in question seems to be in an unsupported state. The apt version is old, and the upgrade seems to have been attempted with apt instead of do-release-upgrade (as do-release-upgrade would tell you to upgrade first).

apt in trusty does not contain the bash completion, and apt in xenial has appropriate Replaces on the bash-completion that is causing the conflict here.

[Launchpad Janitor (janitor)]

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