Our implementation of systemd cgroups is mixture of systemd api and plain filesystem api. It's hard to keep it up to date with systemd and it already contains some nasty bugs with new versions. Ideally it should be replaced with some daemon flag which will allow to set parent systemd slice. Signed-off-by: Alexander Morozov <lk4d4@docker.com> Upstream-commit: 419fd7449fe1a984f582731fcd4d9455000846b0 Component: engine