package flashplugin-installer 10.1.53.64ubuntu0.10.04.1 cannot install/upgrade over proxy

Binary package hint: flashplugin-nonfree

I noticed Flash wasn't working in Firefox after installing updates. I typed
  sudo dpkg-reconfigure flashplugin-installer
in a terminal. It then tried to download http://archive.canonical.com/pool/partner/a/adobe-flashplugin/adobe-flashplugin_10.1.53.64.orig.tar.gz without making use of the configured http_proxy.

I was able to wget that file successfully in the same terminal. I managed to get the package to install by hard-coding my proxy settings at line 65 of /var/lib/dpkg/info/flashplugin-installer.postinst, when it writes a temporary wgetrc file. However, the http_proxy variable was not set when that script was run.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: flashplugin-installer 10.1.53.64ubuntu0.10.04.1
ProcVersionSignature: Ubuntu 2.6.32-22.36-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-22-generic i686
Architecture: i386
Date: Tue Jun 15 08:59:09 2010
EcryptfsInUse: Yes
ProcEnviron:
 PATH=(custom, user)
 LANG=en_GB.utf8
 SHELL=/bin/bash
SourcePackage: flashplugin-nonfree