Comment 3 for bug 1550502

dpkg: considering deconfiguration of ifupdown, which would be broken by installation of systemd ...
dpkg: yes, will deconfigure ifupdown (broken by systemd)
dpkg: considering deconfiguration of udev, which would be broken by installation of systemd ...
dpkg: yes, will deconfigure udev (broken by systemd)
Preparing to unpack .../systemd_229-1ubuntu4_amd64.deb ...
De-configuring udev (225-1ubuntu9) ...
dpkg: error processing archive /var/cache/apt/archives/systemd_229-1ubuntu4_amd64.deb (--unpack):
 subprocess installed pre-removal script returned error exit status 2

Do you still have that machine in this broken state? Please run

   sudo sed -i '2 s/^/set -x/' /var/lib/dpkg/info/systemd.preinst
   sudo apt-get -f install

and copy&paste the entire output.