broken alternatives setting in postinst prevents upgrade

[Martin-Éric Racine]

Binary package hint: gnash

$ LC_ALL=C sudo dpkg -a --configure
Setting up browser-plugin-gnash (0.8.8-6ubuntu1) ...
update-alternatives: using /usr/lib/gnash/libgnashplugin.so to provide /usr/lib/mozilla/plugins/flashplugin-alternative.so (iceape-flashplugin) in auto mode.
update-alternatives: error: alternative link /usr/lib/mozilla/plugins/flashplugin-alternative.so is already managed by iceape-flashplugin.
dpkg: error processing browser-plugin-gnash (--configure):
 subprocess installed post-installation script returned error exit status 2

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: browser-plugin-gnash 0.8.8-6ubuntu1
ProcVersionSignature: Ubuntu 2.6.37-7.18-generic 2.6.37-rc3
Uname: Linux 2.6.37-7-generic i586
Architecture: i386
Date: Mon Nov 29 21:07:55 2010
ProcEnviron:
 LANGUAGE=fi_FI:fi:en_US:en
 PATH=(custom, user)
 LANG=fi_FI.UTF-8
 SHELL=/bin/bash
SourcePackage: gnash