Safe way to upgrade systemd in Xenial?

Xenial (16.04) has systemd-229. Unfortunately, that version seems to still have a bug that prevents KillUserProcesses from working properly. See this bug.

So, I want to upgrade to at least 230, or even newer.

Since systemd is such a core plumbing to Ubuntu, how do I do this safely?

(edit: fixed version number)

You have five options. You will need to decide which criteria (LTS, safe, easy, fast) are more important - no option meets all of them:

1. Wait for the next LTS. This is safe, but it does not fix your problem.

2. Install a newer non-LTS release. This is also safe, but you seem to not like this one.

3. File a Stable Release Update request on Launchpad to get the fix backported to 16.04. This is reasonably safe - SRUs are well-tested. SRUs take time, and may be rejected entirely by the developers.

4. Try installing a systemd package from a newer release of Ubuntu. This is almost certainly not safe at all, and risks breaking your system horribly.

5. Learn to compile systemd, and install a newer version. This requires great skill and patience to do properly. Many, many opportunities for breakage and frustration, not safe at all unless you have years of experience with compiling and init.