aptdaemon error (software-center) TypeError: 'dbus.Struct' object does not support item assignment

Binary package hint: aptdaemon

Software center will not install a single .deb (downloaded or otherwise) if the package is not in the apt-cache
This has been going on for quite some time though the error may have changed
(previously reported against sc in bug 706041

reported error
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/aptdaemon/worker.py", line 884, in simulate
    return self._simulate_helper(trans, status_path)
  File "/usr/lib/python2.7/dist-packages/aptdaemon/worker.py", line 987, in _simulate_helper
    trans.packages[PKGS_INSTALL] = [deb.pkgname]
TypeError: 'dbus.Struct' object does not support item assignment

From sc debug

Traceback (most recent call last):
  File "/usr/lib/python2.7/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/usr/lib/python2.7/multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/share/software-center/softwarecenter/db/reviews.py", line 238, in _get_reviews_threaded
    origin = self.cache.get_origin(app.pkgname)
  File "/usr/share/software-center/softwarecenter/apt/aptcache.py", line 190, in get_origin
    for origin in self._cache[pkgname].candidate.origins:
  File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 161, in __getitem__
    raise KeyError('The cache has no package named %r' % key)
KeyError: "The cache has no package named u'libdvdcss-dev'"

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: aptdaemon 0.40+bzr541-0ubuntu2
ProcVersionSignature: Ubuntu 2.6.38-1.27-generic 2.6.38-rc2
Uname: Linux 2.6.38-1-generic i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Fri Jan 28 18:42:25 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20110120)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
SourcePackage: aptdaemon