[Piuparts-devel] pull: for-holger - lets start work on 0.57

[Andreas Beckmann]

let's make that

Andreas Beckmann (7):
      p: ignore backup files from base-passwd
      scripts-leftovers: preseed pluxml cleanup during purge
      lib/db: _compute_package_state(): compute dep_states once
      lib/db: get_best_package_state(): consider providers as well
      lib/db: test essential-required packages like regular ones
      p-r: mark essential-required as obsolete
      update essential-required list for experimental