Hmmm...it would appear that dpkg-dev and dpkg 1.4.1.8 have to be installed in that order if 1.4.1.6 is already on the system. apt-get tries to install them in the other order. Perhaps this is one of those instances where dpkg (the package) should have "Conflicts: dpkg-dev (<< 1.4.1.8)" in its control file?