rebase -r: do not (re-)generate root commits with `--root` *and* `--onto`

diff --git a/t/t3427-rebase-subtree.sh b/t/t3427-rebase-subtree.sh
index 7a37235768574db87e76b3659ca4cfd39f248563..39e348de163b722c792e1576a4ab2af62757fd79 100755 (executable)
--- a/t/t3427-rebase-subtree.sh
+++ b/t/t3427-rebase-subtree.sh
@@ -93,4 +93,15 @@ test_expect_success 'Rebase -Xsubtree --keep-empty --onto commit' '
        verbose test "$(commit_message HEAD)" = "Empty commit"
 '
 
+test_expect_success 'Rebase -Xsubtree --keep-empty --rebase-merges --onto commit' '
+       reset_rebase &&
+       git checkout -b rebase-merges-onto to-rebase &&
+       test_must_fail git rebase -Xsubtree=files_subtree --keep-empty --rebase-merges --onto files-master --root &&
+       : first pick results in no changes &&
+       git rebase --continue &&
+       verbose test "$(commit_message HEAD~2)" = "master4" &&
+       verbose test "$(commit_message HEAD~)" = "files_subtree/master5" &&
+       verbose test "$(commit_message HEAD)" = "Empty commit"
+'
+
 test_done