package openjdk-7-jre-headless 7u79-2.5.5-0ubuntu1 failed to install/upgrade: trying to overwrite shared '/etc/java-7-openjdk/psfont.properties.ja', which is different from other instances of package openjdk-7-jre-headless:amd64

[jp]

this package, going back to at least 12.04 (~) has always failed to update/upgrade.
when incorporated with a system update xx.04/xx.10 it works okay until the next individual file needs updated.
been reported many times before.

~$ lsb_release -rd
Description: Ubuntu 15.04
Release: 15.04

~$ uname -a
Linux 3.19.0-26-lowlatency #28-Ubuntu SMP PREEMPT Tue Aug 11 14:54:09 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

~$ lsb_release -a
LSB Version: core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch:core-4.1-amd64:core-4.1-noarch:security-4.0-amd64:security-4.0-noarch:security-4.1-amd64:security-4.1-noarch
Distributor ID: Ubuntu
Description: Ubuntu 15.04
Release: 15.04
Codename: vivid

~$ java -version
Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar
java version "1.7.0_79"
OpenJDK Runtime Environment (IcedTea 2.5.5) (7u79-2.5.5-0ubuntu1)
OpenJDK 64-Bit Server VM (build 24.79-b02, mixed mode)

dpkg --list | grep -i jdk
ii icedtea-6-jre-cacao:amd64 6b36-1.13.8-0ubuntu1~15.04.1 amd64 Alternative JVM for OpenJDK, using Cacao
ii icedtea-6-jre-jamvm:amd64 6b36-1.13.8-0ubuntu1~15.04.1 amd64 Alternative JVM for OpenJDK, using JamVM
ii openjdk-6-jdk:amd64 6b36-1.13.8-0ubuntu1~15.04.1 amd64 OpenJDK Development Kit (JDK)
ii openjdk-6-jre:amd64 6b36-1.13.8-0ubuntu1~15.04.1 amd64 OpenJDK Java runtime, using Hotspot JIT
ii openjdk-6-jre-headless:amd64 6b36-1.13.8-0ubuntu1~15.04.1 amd64 OpenJDK Java runtime, using Hotspot JIT (headless)
ii openjdk-6-jre-lib 6b36-1.13.8-0ubuntu1~15.04.1 all OpenJDK Java runtime (architecture independent libraries)
ii openjdk-7-jre-headless:amd64 7u79-2.5.5-0ubuntu1 amd64 OpenJDK Java runtime, using Hotspot JIT (headless)
rc openjdk-7-jre-headless:i386 7u55-2.4.7-1ubuntu1~0.12.04.2 i386 OpenJDK Java runtime, using Hotspot JIT (headless)

ProblemType: Package
DistroRelease: Ubuntu 15.04
Package: openjdk-7-jre-headless 7u79-2.5.5-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-26.28-lowlatency 3.19.8-ckt4
Uname: Linux 3.19.0-26-lowlatency x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.17.2-0ubuntu1.3
Architecture: amd64
Date: Wed Sep 2 07:31:24 2015
DpkgHistoryLog:
 Start-Date: 2015-09-02 07:31:11
 Commandline: aptdaemon role='role-commit-packages' sender=':1.77'
 Upgrade: libgnutls-openssl27:amd64 (3.3.8-3ubuntu3, 3.3.8-3ubuntu3.1), libgnutls-deb0-28:amd64 (3.3.8-3ubuntu3, 3.3.8-3ubuntu3.1), libgnutls-deb0-28:i386 (3.3.8-3ubuntu3, 3.3.8-3ubuntu3.1), libexpat1-dev:amd64 (2.1.0-6ubuntu1, 2.1.0-6ubuntu1.1), openjdk-7-jre-headless:amd64 (7u79-2.5.5-0ubuntu1, 7u79-2.5.6-0ubuntu1.15.04.1), libexpat1:amd64 (2.1.0-6ubuntu1, 2.1.0-6ubuntu1.1), libexpat1:i386 (2.1.0-6ubuntu1, 2.1.0-6ubuntu1.1)
DuplicateSignature: package:openjdk-7-jre-headless:7u79-2.5.5-0ubuntu1:trying to overwrite shared '/etc/java-7-openjdk/psfont.properties.ja', which is different from other instances of package openjdk-7-jre-headless:amd64
ErrorMessage: trying to overwrite shared '/etc/java-7-openjdk/psfont.properties.ja', which is different from other instances of package openjdk-7-jre-headless:amd64
InstallationDate: Installed on 2012-09-06 (1090 days ago)
InstallationMedia: Ubuntu-Studio 12.04 "Precise Pangolin" - Release amd64 (20120425)
RelatedPackageVersions:
 dpkg 1.17.25ubuntu1
 apt 1.0.9.7ubuntu4.1
SourcePackage: openjdk-7
Title: package openjdk-7-jre-headless 7u79-2.5.5-0ubuntu1 failed to install/upgrade: trying to overwrite shared '/etc/java-7-openjdk/psfont.properties.ja', which is different from other instances of package openjdk-7-jre-headless:amd64
UpgradeStatus: Upgraded to vivid on 2015-04-25 (130 days ago)
mtime.conffile..etc.java.7.openjdk.security.java.security: 2015-04-15T15:08:21
mtime.conffile..etc.java.7.openjdk.sound.properties: 2014-08-01T16:01:42