Comment 30 for bug 1671951

I tested with your single-file approach and that also fails. Note that bionic now has systemd 237, so maybe something is missing (or regressed) ?

$ apt-cache policy systemd
systemd:
  Installed: 237-3ubuntu10.26
  Candidate: 237-3ubuntu10.26
  Version table:
 *** 237-3ubuntu10.26 500
        500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     237-3ubuntu10.25 500
        500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
     237-3ubuntu10.19 500
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     237-3ubuntu10 500
        500 http://nova.clouds.archive.ubuntu.com/ubuntu bionic/main amd64 Packages