* prepare a branch in iuk.git that updates UDF generation code (replace dl.a.b.o with mirrors.wikimedia) [i]
* keep the fallback DNS pool running: it's still used by Tails Upgrader and we "support" skipping an upgrade (from 3.6 to 3.7) so it must remain working until 3.6 users can upgrade directly to 3.8
* prepare a branch against mirrors.git to document the new setup and drop the obsolete crap