Merge pull request #4538 from fbuihuu/confirm-spawn-fixes

Confirm spawn fixes/enhancements

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

diff --cc src/core/execute.h
Simple merge

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

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

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

diff --cc src/core/unit.h
Simple merge

diff --cc src/shared/nsflags.c
Simple merge