Comment 6 for bug 520520

We will build in 2 phases, each with different dependency requirements:

phase1: depends phase1, main_archive
phase2: depends phase2, phase1, main_archive

The +admin form on the copy archive page can then set up to include itself and other archives (phase1, phase2 in this case). archivedependencies.py/get_sources_list_for_building() needs altering so that it puts these dependencies in the right order.

This means we need to publish rebuilds in real-time, so will need a cron job on mcmurdo (where they're being published). We also need a new config item to complement base_url, e.g. copy_archive_base_url)

When fixing IArchive.archive_url, it should make sure the copy archive name is in the path so there can be more than one of them on the same machine.