Merge branch 'en/rebase-merge-on-sequencer'

"git rebase --merge" as been reimplemented by reusing the internal
machinery used for "git rebase -i".

* en/rebase-merge-on-sequencer:
  git-rebase.txt: update to reflect merge now implemented on sequencer

Author: gitster

Documentation/git-rebase.txt

@@ -554,8 +554,6 @@ commit started empty (had no changes relative to its parent to
 start with) or ended empty (all changes were already applied
 upstream in other commits).
 
-The merge backend does the same.
-
 The interactive backend drops commits by default that
 started empty and halts if it hits a commit that ended up empty.
 The `--keep-empty` option exists for the interactive backend to allow