package libavahi-compat-libdnssd1:amd64 0.6.31-4ubuntu4 failed to install/upgrade: package is in a very bad inconsistent state; you should reinstall it before attempting configuration

[rwnairn]

I have installed Dropbox and noticed it doesn't show in the system tray as a running app. Neither does the Copy.com agent. Running a sudo apt-get install libappindicator1 gives error.

ProblemType: Package
DistroRelease: Ubuntu 15.04
Package: libavahi-compat-libdnssd1:amd64 0.6.31-4ubuntu4
ProcVersionSignature: Ubuntu 3.19.0-26.28-generic 3.19.8-ckt4
Uname: Linux 3.19.0-26-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.3
AptOrdering:
 libavahi-compat-libdnssd1: Configure
 NULL: ConfigurePending
Architecture: amd64
Date: Sun Aug 30 13:51:01 2015
DpkgTerminalLog:
 dpkg: error processing package libavahi-compat-libdnssd1:amd64 (--configure):
  package is in a very bad inconsistent state; you should
  reinstall it before attempting configuration
DuplicateSignature: package:libavahi-compat-libdnssd1:amd64:0.6.31-4ubuntu4:package is in a very bad inconsistent state; you should reinstall it before attempting configuration
ErrorMessage: package is in a very bad inconsistent state; you should reinstall it before attempting configuration
InstallationDate: Installed on 2015-08-23 (7 days ago)
InstallationMedia: Ubuntu-GNOME 15.04 "Vivid Vervet" - Release amd64 (20150422)
RelatedPackageVersions:
 dpkg 1.17.25ubuntu1
 apt 1.0.9.7ubuntu4.1
SourcePackage: avahi
Title: package libavahi-compat-libdnssd1:amd64 0.6.31-4ubuntu4 failed to install/upgrade: package is in a very bad inconsistent state; you should reinstall it before attempting configuration
UpgradeStatus: No upgrade log present (probably fresh install)