Merge pull request #18601 from keszybz/env-assign-cleanup

Envvar assignment cleanup

diff --cc src/core/load-fragment.c
Simple merge

diff --cc src/core/main.c
Simple merge

diff --cc src/core/manager.c
Simple merge

diff --cc src/home/homectl.c
Simple merge

diff --cc src/nspawn/nspawn.c
Simple merge