if (ns == UNIT_FAILED && os != UNIT_FAILED)
set_put(u->manager->failed_units, u);
else if (os == UNIT_FAILED && ns != UNIT_FAILED)
if (ns == UNIT_FAILED && os != UNIT_FAILED)
set_put(u->manager->failed_units, u);
else if (os == UNIT_FAILED && ns != UNIT_FAILED)