Comment 21 for bug 146943

1. When did you start update?
The bug should be fixed.
Please post your /etc/apt/sources.list
Maybe you use a mirror that is not updated yet.
What does "apt-cache policy python-apt" say?

2. Try this:
> cd /var/cache/apt/archives/
> sudo dpkg -i python-central_0.5.15ubuntu2_all.deb
> sudo dpkg -i python-apt_0.7.3.1ubuntu4_*.deb # Or the version number you have
> sudo dpkg -i dpkg_1.14.5ubuntu16_*.deb
> sudo dpkg --configure -a
> sudo apt-get dist-upgrade