5.1-RELEASE critical alpha bug

[Bobo the Dancing Bear]

The 5.1-rc1 and 5.1-RELEASE boot floppy images for alpha (kern.flp) are
not valid boot images.  I get the following error when trying to boot from
verifiably bootable (with 4.8, 5.0, and linux) floppy disks:

>>> boot dva0
block 0 of dva0.0.0.0.1 is not a valid boot block
bootstrap failure

The machine in question is a AXPpci/ noname motherboard with SCSI cdrom
and IDE hard disks, running the latest AXPpci SRM firmware (v1.6).  All
the freebsd and linux floppies were created with dd on x86 linux.