Comment 1 for bug 146956

Confirming, saw this on laptop and now also on my desktop computer when upgrading from Feisty to Gutsy: The laptop was i386 and this one is amd64. From term.log:

Preparing to replace lsb-release 3.1-22ubuntu3 (using .../lsb-release_3.1-23.1ubuntu3_all.deb) ...
Unpacking replacement lsb-release ...
Preparing to replace python-apt 0.6.20ubuntu16 (using .../python-apt_0.7.3.1ubuntu2_amd64.deb) ...
dpkg-query: jäsennysvirhe, tiedostossa `/var/lib/dpkg/updates/0013' lähellä riviä 2 paketti `libc6':
 `triggers-pendi' ei ole sallittu kolmas (tila) sana `status' -kentässä:lle
Traceback (most recent call last):
  File "/usr/bin/pycentral", line 1394, in <module>
    main()
  File "/usr/bin/pycentral", line 1388, in main
    rv = action.run(global_options)
  File "/usr/bin/pycentral", line 955, in run
    pkg.read_version_info()
  File "/usr/bin/pycentral", line 542, in read_version_info
    raise PyCentralError, "package has no field Python-Version"
__main__.PyCentralError: package has no field Python-Version
dpkg: varoitus - old pre-removal script palautti virhetilakoodin 1
dpkg - trying script from the new package instead ...
ä 2 paketti `libc6':
dpkg: error processing /var/cache/apt/archives/python-apt_0.7.3.1ubuntu2_amd64.deb (--unpack):
 aliprosessi new pre-removal script palautti virhetilakoodin 1
  File "/usr/bin/pycentral", line 879, in run
dpkg: virhe jälkipuhdistuksessa:
  aliprosessi post-installation script palautti virhetilakoodin 1
Preparing to replace pkg-config 0.21-1build1 (using .../pkg-config_0.22-1_amd64.deb) ...
eb (--unpack):
Unpacking replacement pkg-config ...
ä 2 paketti `libc6':
Preparing to replace libglib2.0-dev 2.12.11-0ubuntu1 (using .../libglib2.0-dev_2.14.1-1ubuntu1_amd64.deb) ...
Unpacking replacement libglib2.0-dev ...
Preparing to replace libglib2.0-0 2.12.11-0ubuntu1 (using .../libglib2.0-0_2.14.1-1ubuntu1_amd64.deb) ...
Unpacking replacement libglib2.0-0 ...

Sorry for Finnish in there, but basically it's identical to original reporter's error message (although only once). On both machines, I used Update Manager for the upgrade, and it popped up a closable window with the error message while continuing to install on the background. Locale is fi_FI.UTF-8.

Because of this (?) error windows also pop about dependency problem with update-manager, update-manager-core, update-notifier, gdebi-core, gdebi, unattended-upgrades, python-software-properties, software-properties-gtk, gnome-app-install, language-selector, ubuntu-desktop, command-not-found, python-launchpad-bugs, python-apport, apport, apport-gtk, apturl, ubufox later on during the installation. Also those may be closed separately and the installation continues.

Finally a error pops that "Updates could not be installed" (in Finnish), consider using dpkg --configure -a etc. It also recommends filing a bug against update-manager, but since it only points to installArchives() I think python-apt is a proper place for this bug.