package phpmyadmin 4:3.4.10.1-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 128

[Fiable.biz]

When trying to install phpMyAdmin using Ubuntu software centre, I got the choice between "Abort", "Retry" and "Skip" (possibly a third useless one), with no explanation. A possible cause is that MySQL was already installed with a root password, but I was not asked for the password.

ProblemType: Package
DistroRelease: Ubuntu 12.04
Package: phpmyadmin 4:3.4.10.1-1
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28
Uname: Linux 3.2.0-31-generic x86_64
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
Date: Fri Oct 12 16:09:14 2012
ErrorMessage: subprocess installed post-installation script returned error exit status 128
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
SourcePackage: phpmyadmin
Title: package phpmyadmin 4:3.4.10.1-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 128
UpgradeStatus: No upgrade log present (probably fresh install)