Please see rsbackup in git for detailed change history.
PRUNING section of the man page
      for further information.  The default behavior matches previous
      versions.
      Fixes
      issue #7.min-backups
      and prune-age directives are now deprecated in
      their current form and will produce a warning.  In some future
      version they will be removed.  Instead,
      use prune-parameter min-backups
      and prune-parameter prune-age.public,
      always-up, check-mounted and
      traverse directives now take an explicit boolean
      argument.  Using them without an argument is now deprecated (but
      has not changed in meaning).  In some future version the
      argument will become mandatory.rsync-timeout and hook-timeout
      directives are now inherited, as documented.
      ssh-timeout becomes inherited too.  The
      sendmail directive is now documented.-”.--dump-config --verbose now annotates its
      output.  Some options missed by --dump-config are
      now output.rsbackup.cron will always run the prune and
      report steps, even if the earlier steps fail.rsbackup-snapshot-hook copes better with
      aliases for logical volumes.  Fixes issue
      #23.report-prune-logs configuration setting.--dry-run mode.  The
      environment variables RSBACKUP_ACT can be used by
      the script to distinguish the two situations.
      rsbackup-snapshot-hook has been modified
      accordingly.  Fixes issue
      #9.check-mounted option verifies that a volume
      is mounted before backing it up.  Fixes issue
      #13.store-pattern option allows stores to be
      specified by a glob pattern instead of individually.  Fixes issue
      #5.stylesheet and colors options
      allow operator control of the stylesheet and coloration in the
      HTML version of the report.  Fixes issue
      #6.lock are now documented.  Fixes issue
      #20.rsbackup no longer
      depend on Bash.priority option.  Fixes issue
      #19.always-up option is
      slightly modified: backups of always-up hosts are attempted,
      resulting in error logs, even if they do not seem to be
      available.  Fixes issue
      #22.--database option allows the path to the
      database to be overridden.--dump-config
      option.rsbackup.cron when it has been removed.  Fixes Debian bug
      #766455.--store are now more accurate.  Fixes issue
      #10.include command now skips filenames that
      start with #.  Fixes issue
      #12.rsbackup-snapshot-hook no longer fails if
      fsck finds and fixes errors.  It is also now
      tested.  Fixes issue
      #15.--dump-config option to verify
      configuration file parse.--check option to
      rsbackup-mount.--force option no longer implies the
      --verbose option.  (This was a bug.)RSBACKUP_STATUS value passed to
      post-backup hook.  (Bug spotted by Jacob Nevins.)--retire no longer fails if a host directory
      has already been removed.rsbackup as some other operation.--html option (Jon Amery).--prune-incomplete option, which
      wouldn't work in the absence of some other option (Jacob
      Nevins).pre-access-hook and
      post-access-hook options support running “hook”
      scripts before and after any access to backup storage
      devices.pre-backup-hook and
      post-backup-hook options support running “hook”
      scripts before and after a backup.  Although these can be used
      for any purpose, the motivation is to enable the creation of LVM
      snapshots of the subject filesystems (and their destruction
      afterwards), resulting in more consistent backups.  The supplied
      hook script only knows about the Linux logical volume
      system.devices option allows a host or volume
      to be restricted to a subset of devices, identified by a
      filename glob pattern.rsync-timeout option allows a time
      limit to be imposed on a backup.check-file option allows backups of a
      volume to be suppressed when it is not available (for instance,
      because it is only sometimes mounted).--verbose (and therefore
      --dry-run) is now more verbose.--text and --html now accept
      - to write to standard output.rsbackup-mount now supports unencrypted devices
      and separate key material files (contributed by Matthew
      Vernon).--prune honours command-line selections again.--logs option controls which logfiles
      are included in the HTML report.  The default is to only include
      the logfile of the most recent backup if it failed.  Also, if
      the most recent attempt to backup a volume to a given device
      failed, its heading is highlighted (in red).--version
      options.  Single-letter command line options are now supported
      (in fact they existed in many cases already but weren’t
      documented).. and ....incomplete files used by the Perl script
      to indicate partial backups are now created by the C++ version
      too.  They are created both before starting a backup and before
      pruning it.  rsbackup itself does not rely on them itself but
      they are an important hint to the operator when doing bulk
      restores.--warn-store is given, but if no
      configured store is present then the problems found with all
      configured stores are listed.  The documentation on how to set
      up stores has also been clarified.rsbackup has been rewritten in C++.  The behaviour
    is largely same except as follows:
--text option generates a plaintext version
      of the report.  In addition the email report includes both the
      text and HTML versions.--prune-unknown is removed.  It is replaced by
      --retire, which is used to remove backups of
      volumes (and hosts) that are no longer in use and
      --retire-device which is used to remove logs for
      devices that are no longer in use.rsync command now includes the
      --delete option, meaning that interrupted backups
      no longer include stray files from the first attempt..incomplete files are no longer created.
      Instead the logs are used to distinguish complete from
      incomplete backups.--warn- options to control what is
      warned about.always-up option to indicate that a host is
      expected to always be available to back up.