usetup: bootsector is overwritten with garbage when creating booting floppy

Created an attachment (id=7970)
Screenshot of the bad boot sector.

When creating a boot floppy with the ReactOS setup, the resulting disk is not bootable and can not be read. Inspecting the disk, the Bios Parameter Block contains garbage.

Replicated this under VirtualBox and on real hardware.

Regression testing shows:

54202 - works (ignoring that it was already suffering from CORE-5893)
54203 - no build
54204 - no build
54205 - no build
54206 - fails

Although I don't see why this would change setup, as 54203 and the builds following it have to do with win32k/user keyboard layout code.

On top of that, I could have sworn I had tested a build some time after that to verify if CORE-5893 was fixed, but I must have been mistaken.

Attaching a screenshot of the bad boot sector. Notice that the text "ScsiPortReadPortUshort ? PortReadRegisterBufferUchar Sc1" shouldn't be there.