Merge branch 'jk/rebase-quiet-noop' into maint

"git rebase --quiet" was not quite quiet when there is nothing to
do.

* jk/rebase-quiet-noop:
  rebase: silence "git checkout" for noop rebase

Author: gitster

git-rebase.sh

@@ -582,7 +582,7 @@ then
 		# Lazily switch to the target branch if needed...
 		test -z "$switch_to" ||
 		GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $switch_to" \
-			git checkout "$switch_to" --
+			git checkout -q "$switch_to" --
 		say "$(eval_gettext "Current branch \$branch_name is up to date.")"
 		finish_rebase
 		exit 0