Merge remote branch 'drkranz/overrides' into merge

Merge remote branch 'drkranz/overrides' into merge

* drkranz/overrides:
  Move more objects into get_packages_from_ftp()
  Pipes ftw!
  Add dak override-disparity command to cron.daily
  override_disparity.py: display YAML output
  Move common code to the new get_packages_from_ftp()
  override_disparity.py: generate a list of override disparities
  override.py: check override compliance
  ls.py: let -a source display sources only (#458186)

Signed-off-by: Joerg Jaspert <joerg@debian.org>