* Add (extra-)override parsing to the preinstalled pool to make sure we get task headers in the local pool for tasksel (LP: #819899) * Move temp directories under config so they get cleaned properly * Invoke apt-get update once with only the sources.list fragment for the local archive, so our package/task selection more closely mimics the CD experience (LP: #985258, #985737, #985280, #819900) * Write out a standard sources.list entry for preinstalled systems that's similar to the one generated by installers (LP: #985291)