Comment 2 for bug 1023437

I managed to reproduce here with a minimal 12.04 install manually upgrading (apt-get dist-upgrade) to quantal.

Just a few notes.
 - /etc/init.d/networking is a sysvinit script in netbase < 5.0
 - /etc/init.d/networking was dropped from netbase >= 5.0
 - /etc/init.d/networking was added to ifupdown >= 0.7.1
 - in ifupdown, /etc/init.d/networking is a symlink to /lib/init/upstart-job

ifupdown 0.7.1ubuntu1 declares:
Replaces: netbase (<< 5.0)
Breaks: netbase (<< 5.0)

Which should be enough to have dpkg cope with the upgrade. It's expected to do the following:
 - unpack new netbase
 - unpack new ifupdown
 - consider /etc/init.d/networking as now being part of ifupdown
 - configure netbase
 - configure ifupdown