Updating my source to 2.6.7 I see that you applied some
nonsense garbage patch. Please undo.

[ Note by Linus: the fact that DOS_EXTENDED_PARTITION is 5, and we're
  iterating over slots 1-4 in the partition table, are two totally
  unrelated things. Using the symbolic constant does indeed not make
  any sense at all here, as Andries so eloquently points out. ]