Basically, the patch (named 0005-Make-root-s-home-directory-configurable.patch in thud) deteriorated over the various systemd uprevs to the point it no longer does what it was meant to do. It merely adds a define through the meson build system but the code doesn't actually uses it.

Preconditions/Environment
-------------------------
systemd in DISTRO_FEATURES

Triggering Action/Cause
-----------------------
Various, basically ROOT_HOME (defined in bitbake.conf) no longer makes it into systemd's binaries.

Expectation
-----------
Systemd should use "/home/root" (or the value of ROOT_HOME) instead of "/root" 

Actual Result
-------------
"/root" is hard-coded for root's home dir.

Reproducibility
---------------
1/1


Refer to thread: https://lists.yoctoproject.org/pipermail/poky/2019-January/011614.html