Comment 0 for bug 172609

Binary package hint: update-manager

The machine in question is an ia64 host which lists only a local mirror in sources.list, and that mirror only has -security and -updates (in addition to the base release), no -backports. The machine _does_ have access to the public network, and is therefore able to access public mirror sites as well.

do-release-update eventually generates /etc/apt/sources.list.d/prerequists-sources.list with the following:
  # sources.list fragment for pre-requists (one with countrymirror, one fallback)
  deb http://us.archive.ubuntu.com/ubuntu feisty-backports main/debian-installer
  #deb http://archive.ubuntu.com/ubuntu feisty-backports main/debian-installer
  # below is just for testing
  #deb http://archive.dogfood.launchpad.net/ubuntu feisty-backports main/debian-installer

However, the correct entry for this machine (being ia64) would be:
  deb http://ports.ubuntu.com/ubuntu-ports feisty-backports main/debian-installer

thanks,
lamont