Comment 2 for bug 661820

Here some notes how to rescue the system:

Boot with the live CD.

Mount the hard-disc:
mount /dev/sda1 /mnt

Mount system folders into sda1:
mount –t proc none /mnt/proc
mount –o bind /dev /mnt/dev
mount –o bind /sys /mnt/sys

Change the apparent disk root directory:
chroot /mnt

Now delete all occurences of mdadm:
find / -name mdadm | xargs rm -r

Now call:
update-initramfs -u

With this a new ramfs is created without mdadm - the system boots again.