MODULES: lib1, main

STEP 0:
    libs: lib1, main
    dirty js modules: lib1, main
    dirty js files:   lib1/l1, main/m, main/m.export, main
STEP 1:
    libs: lib1, main
    dirty js modules: lib1, main
    dirty js files:   lib1/l1, lib1/l1.export, lib1, main/m
STEP 2..3:
    libs: lib1, main
    dirty js modules: lib1, main
    dirty js files:   lib1/l1, lib1/l1.export, main/m
STEP 4:
    libs: lib1, main
    dirty js modules: lib1, main
    dirty js files:   lib1/l1, main/m