The same thing has happened in another install using d-i (#258889, merged with #249371).
From the partman log file: <snip> Model: TOSHIBA MK2016GAP Path: /dev/ide/host0/bus0/target0/lun0/disc Sector size: 512 Sectors: 39070080 Sectors/track: 63 Heads: 240 Cylinders: 2584 Partition table: yes Type: loop Partitions: # id length type fs path name (0,0,0) (2583,239,62) 1 0-20003880959 20003880960 primary fat16 /dev/ide/host0/bus0/target0/lun0/disc </snip>
