It turns out that all sorts of fun and weird things happen on a modern Linux machine when the system D-Bus daemon dies, even on a server. As they say, ask me how I know.
The opposite is fun, too: when there's a system #DesktopBus broker running but it's not a systemd system, and logging in through a chain of intertwined mechanisms tries to auto-start #systemd.
One can get possibly simpler still. I got here because all of the noise and delay that pam_systemd.so makes on a modern #Debian system. And gvim. gvim pausing for up to 25 seconds waiting for #DesktopBus services; and pam_systemd doing the same at login. Some background: [Continued…] #nosh