1level 1: variable 0, env 1 2level 2: variable 1, env 2 3level 3: variable 2, env 3 4: set-env-same 5ok 6: set-env-different 7make: Cannot override read-only global variable ".MAKE.LEVEL.ENV" with a command line variable 8 in make[1] in directory "<curdir>" 9make: Fatal errors encountered -- cannot continue 10make: stopped making "ok" in unit-tests 11set-env-different: exit 1 12exit status 0 13