Comment 11 for bug 324987

Here are instructions to reproduce the issue in a KVM/QEMU virtual machine using a live-CD ISO image. They create a qcow2 image, mount it using nbd, create the 'faulty' partition table using 'fdisk -u', and then start the VM guest with the live-CD.

qemu-img create -f qcow2 ubuntu-jaunty-install-test.qcow2 3500M
sudo modprobe nbd
sudo qemu-nbd -c /dev/nbd0 ubuntu-jaunty-install-test.qcow2
echo -e "o\nn\np\n1\n\n+100M\nt\n27\nn\np\n2\n\n+250M\nt\n2\n7\nn\np\n3\n\n+250M\nn\ne\n\n\nn\n\n+400M\nn\n\n\np\nw\n" | sudo fdisk -u /dev/nbd0
sudo nbd-client -d /dev/nbd0
sudo losetup /dev/loop2 jaunty-desktop-amd64-alpha4.iso

kvm -m 512 -boot d -cdrom /dev/loop2 -hda ubuntu-jaunty-install-test.qcow2

# when finished, do:
sudo losetup -d /dev/loop2

Start the desktop installer.
When the Partitioning page is reached, select "Manual"
Assign sda3 to /boot
Assign sda5 to swap
Assign sda6 to /

Move on to the installation phase. The partitioner will start-up and then close, returning to the "Prepare disk space" page.

In a terminal "cat /proc/partitions" will show that the logical partitions in the sda4 extended container have gone missing.