There are at least three bugs here.

1. The last stboot.iso is not using ttyS0, perhaps bc build hickups. I didn't want to task clean-all or even task clean because I thought we need the signing keys from the previous stage. Not sure that's correct.
2. The stboot "OS package pointer" DEBUG printout is broken, see PNG file from console: stboot-after-stprov.png
3. The ospkg is not downloaded successfully, probably due to network configuration.

The third bug might not be a bug after all, other than the wrong link being served from the test web server. At least it's not network related as suggested above.