First, an answer that I happen to have handy to Hans's question from Feb 2019:
"TBH, I'm not an expert at all in this area, I never figured out yet how all these systemd<->init-script compatibility layers work yet." Neither am I an expert, and I'd really prefer not needing to become one, but from what I just read in the systemd-sysv-generator man page, the answer would have to be "poorly, in general". I was specifically looking into a timeout on shutdown, and it's problematic at least in part because the generator does not process the $syslog item from the LSB header, so the hang happens in a black hole. The last visible message other than the truncated one about the "LSB stop job ... xendomains" on the console was one that seemed to be about the end of block device availability, which would account for the shutdown hang in xendomains very handily. The screen was apparently cleared just before that, which I guess is systemd being "helpful". As opposed to many things with which it actually is helpful <sigh>. Yes, the shutdown hang is a different issue, but I'm going to hope that the real systemd units mentioned in this bug will fix my problem, too. -- As economics is known as The Miserable Science, software engineering should be known as The Doomed Discipline, doomed because it cannot even approach its goal since its goal is self-contradictory. -- Edsger Dijkstra