Yesterday I did my quarterly update of the software on 3 virtual machines
running debian/testing and rdiff-backup was updated from 2.2.2-1 to 2.2.6-1.
Today when I looked at the log output from my nightly backup scripts emailed to
me from these machines, I see that every invocation of rdiff-backup is now
producing the message:
WARNING: Server will be called with deprecated command line interface to
guarantee compatibility. It might lead to a deprecation warning from newer
rdiff-backup versions. Use '--api-version 201' (or higher) to avoid it.