lsbsi build restartability

We appear to have lost build restartability in the lsbsi. =20
This is the second time I tried a make after an interrupted
build in phase3 or phase4 (which don't have any of the=20
"did you pass the barrier" logic of phase2) where it just
blithely began from the beginning of the phase, despite the
stamp files clearly being present in the
..../si/lsbsi-intermediate-{arch}/tmp directory.

Any ideas?  Do I need to file a bug?