I apoligise. I have forgotten about a small detail with usb floppy installs: They don't work unless you have a fixed debootstrap-cvs-floppy-udeb on them with a few additional commands.
Until bug #215169 is fixed, the boot floppy will not support USB floppies. Probably no need for all that debugging I suggested, though you might still want to make sure you have a /dev/scsi/... tree. I can also send you a bootfloppy with a fixed udeb on it if you'd like to try it. -- see shy jo
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