I just encountered this bug on lenny. For anyone who doesn't know, the temporary work around for this is to update like this as root (or using sudo):
aptitude update -o Acquire::PDiffs=false or apt-get update -o Acquire::PDiffs=false -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
