Guillermo:
One could instead attach controllers to the hierarchy rooted in /sys/fs/cgroup/systemd, for example by mounting it with 'mount -t cgroup -o cpu,name=systemd cgroup /sys/fs/cgroup/systemd' (not with system-manager as process 1), and things would appear to be OK:
It's tempting to do that, and make the adjustments to the current control group location code. But the harsh reality I suspect is that version 1 control groups are on the way out. Let's put it this way: I am targetting Debian Linux, notorious for being behind the times, and even that has a kernel (in Debian 8 backports, admittedly) with version 2 control groups now.
I'll save the idea up. But there's other, higher priority stuff to do. I've just finally turned unload-when-stopped into a simple service-control --exit wrapper, for example. (-:
