nspawn: rename UNIFIED_CGROUP_HIERARCHY to SYSTEMD_NSPAWN_UNIFIED_HIERARCHY
We should never have used an unprefixed environment variable name.
All other systemd-nspawn variables have the "SYSTEMD_NSPAWN_" prefix,
and all other systemd variables have the "SYSTEMD_" prefix.
The new variable name takes precedence, but we fall back to checking the
old one. If only the old one is found, a warning is emitted.
In addition, SYSTEMD_NSPAWN_UNIFIED_HIERARCHY="" is accepted as an override
to avoid looking for the old variable name.
We have a variable with the same name ($UNIFIED_CGROUP_HIERARCHY) in tests,
which governs both systemd-nspawn and qemu behaviour. It is not renamed.
projects / thirdparty / systemd.git / commit
