Univention Corporate Server 4.1 erratum 152 (bugfix)

This update addresses the following issues:
* The change from http:// to https:// breaks the old updater from UCS-4.0-4,
  which is still running after the update to 4.1-0. As such all updates stop
  there. Running the same command again continues installing updates, as then
  the new updater is used.
  This update fixes this problem by re-executing the updater after each
  update to guarantee, that the latest version is always used.
* The "dists/**/Packages*" files created for local repositories did contain
  multiple entries for the same package. This breaks the Debian installer and
  other tools like "debootstrap", which use a simpler implementation than
  APT. A filter has been added to filter out old versions and duplicate
  entries.