commit: teach --amend to carry forward extra headers

diff --git a/fast-import.c b/fast-import.c
index f9347f55bac6b2d9a775c165013aa7107790e5f4..8d8ea3c45c0be5481c7b452c27ee0d163d69fb00 100644 (file)
--- a/fast-import.c
+++ b/fast-import.c
@@ -2411,6 +2411,8 @@ static void note_change_n(struct branch *b, unsigned char old_fanout)
        /* <committish> */
        s = lookup_branch(p);
        if (s) {
+               if (is_null_sha1(s->sha1))
+                       die("Can't add a note on empty branch.");
                hashcpy(commit_sha1, s->sha1);
        } else if (*p == ':') {
                uintmax_t commit_mark = strtoumax(p + 1, NULL, 10);
@@ -2712,6 +2714,8 @@ static void parse_new_tag(void)
        from = strchr(command_buf.buf, ' ') + 1;
        s = lookup_branch(from);
        if (s) {
+               if (is_null_sha1(s->sha1))
+                       die("Can't tag an empty branch.");
                hashcpy(sha1, s->sha1);
                type = OBJ_COMMIT;
        } else if (*from == ':') {