As of Git v2.22.0, the `--preserve-merges` backend of `git rebase` will
be officially deprecated in favor of the `--rebase-merges` backend.
Consequently, `git pull --rebase=preserve` will also be deprected. State
this explicitly.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>