make: cond-op-not.mk:30: Not empty evaluates to true.
make: cond-op-not.mk:39: Not space evaluates to false.
make: cond-op-not.mk:44: Not 0 evaluates to true.
make: cond-op-not.mk:53: Not 1 evaluates to false.
make: cond-op-not.mk:60: Not word evaluates to false.
make: cond-op-not.mk:65: Malformed conditional '!'
make: Fatal errors encountered -- cannot continue
make: stopped making "all" in unit-tests
exit status 1