Session-installer installs p7zip, not p7zip-full

On a fresh Ubuntu 12.04 install, trying to open a .7z file results in session-installer asking if you want p7zip to be installed, in order to open the file. The problem is that the p7zip package is unable to open password protected 7z files. The p7zip-full package can, and so should take p7zip's place as the default offering.

Version of sessioninstaller: 0.20+bzr123-0ubuntu2

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: sessioninstaller 0.20+bzr123-0ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic-pae 3.2.14
Uname: Linux 3.2.0-23-generic-pae i686
ApportVersion: 2.0.1-0ubuntu5
Architecture: i386
Date: Tue May 15 22:24:26 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: sessioninstaller
UpgradeStatus: No upgrade log present (probably fresh install)