If you pass the apt-setup/proposed=true boot parameter to the installer, it should install the open-iscsi package from natty-proposed (along with any other packages that have been updated in -proposed, but hopefully that's OK ...).
If you pass the apt-setup/ proposed= true boot parameter to the installer,
it should install the open-iscsi package from natty-proposed (along with
any other packages that have been updated in -proposed, but hopefully
that's OK ...).