git notes merge: --commit should fail if underlying notes ref has moved

diff --git a/builtin/notes.c b/builtin/notes.c
index ee1df7030caceb9ffe2f0500698e7fa95dd196f3..710a89da28bf50c0002f3658f90f674db2e42818 100644 (file)
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -786,7 +786,7 @@ static int merge_abort(struct notes_merge_options *o)
 static int merge_commit(struct notes_merge_options *o)
 {
        struct strbuf msg = STRBUF_INIT;
-       unsigned char sha1[20];
+       unsigned char sha1[20], parent_sha1[20];
        struct notes_tree *t;
        struct commit *partial;
        struct pretty_print_context pretty_ctx;
@@ -803,6 +803,11 @@ static int merge_commit(struct notes_merge_options *o)
        else if (parse_commit(partial))
                die("Could not parse commit from NOTES_MERGE_PARTIAL.");
 
+       if (partial->parents)
+               hashcpy(parent_sha1, partial->parents->item->object.sha1);
+       else
+               hashclr(parent_sha1);
+
        t = xcalloc(1, sizeof(struct notes_tree));
        init_notes(t, "NOTES_MERGE_PARTIAL", combine_notes_overwrite, 0);
 
@@ -818,7 +823,9 @@ static int merge_commit(struct notes_merge_options *o)
        format_commit_message(partial, "%s", &msg, &pretty_ctx);
        strbuf_trim(&msg);
        strbuf_insert(&msg, 0, "notes: ", 7);
-       update_ref(msg.buf, o->local_ref, sha1, NULL, 0, DIE_ON_ERR);
+       update_ref(msg.buf, o->local_ref, sha1,
+                  is_null_sha1(parent_sha1) ? NULL : parent_sha1,
+                  0, DIE_ON_ERR);
 
        free_notes(t);
        strbuf_release(&msg);