The native git option to preserve merge commits during rebase
has been changed from pull.rebase=preserve to pull.rebase=merges.
This changeset in jgit makes the same config change. The old "preserve"
option is no longer recognized and is replaced by new option called
"merges".
This makes jgit's rebase configuration compatible with native git
versions 2.34 and newer where the old "preserve" option has been
removed.
Change-Id: Ic07ff954e258115e76465a1593ef3259f4c418a3
0518a6b0c1