[PATCH v6 9/9] sequencer: fallback to sane label in making rebase todo list

[Doan Tran Cong Danh <congdanhqx@gmail.com>]

In later stage of rebasing, we will make a ref in
refs/rewritten/<label>, this label is extracted from the subject of
current merge commit.

If that subject has forbidden character for refname, git couldn't create
the rewritten ref. One such case is the merge commit subject has
a multibyte character encoded in ISO-2022-JP.

Provide a sane fallback in order to help git-rebase works in such case

Signed-off-by: Doan Tran Cong Danh <congdanhqx@gmail.com>
---
 sequencer.c            | 11 +++++++++--
 t/t3434-rebase-i18n.sh |  2 +-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 2f32b44f52..f664ba727e 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4560,6 +4560,7 @@ static int make_script_with_merges(struct pretty_print_context *pp,
 	while ((commit = get_revision(revs))) {
 		struct commit_list *to_merge;
 		const char *p1, *p2;
+		const char *hex_oid;
 		struct object_id *oid;
 		int is_empty;
 
@@ -4607,9 +4608,15 @@ static int make_script_with_merges(struct pretty_print_context *pp,
 			if (isspace(*p1))
 				*(char *)p1 = '-';
 
+		hex_oid = oid_to_hex(&commit->object.oid);
+
+		if (check_refname_format(label.buf, REFNAME_ALLOW_ONELEVEL) < 0) {
+			strbuf_reset(&label);
+			strbuf_addf(&label, "label-%s", hex_oid);
+		}
+
 		strbuf_reset(&buf);
-		strbuf_addf(&buf, "%s -C %s",
-			    cmd_merge, oid_to_hex(&commit->object.oid));
+		strbuf_addf(&buf, "%s -C %s", cmd_merge, hex_oid);
 
 		/* label the tips of merged branches */
 		for (; to_merge; to_merge = to_merge->next) {
diff --git a/t/t3434-rebase-i18n.sh b/t/t3434-rebase-i18n.sh
index 4b5b128cd6..c7c835cde9 100755
--- a/t/t3434-rebase-i18n.sh
+++ b/t/t3434-rebase-i18n.sh
@@ -45,7 +45,7 @@ test_expect_success 'rebase --rebase-merges update encoding eucJP to UTF-8' '
 	compare_msg eucJP.txt eucJP UTF-8
 '
 
-test_expect_failure 'rebase --rebase-merges update encoding eucJP to ISO-2022-JP' '
+test_expect_success 'rebase --rebase-merges update encoding eucJP to ISO-2022-JP' '
 	git switch -c merge-eucJP-ISO-2022-JP first &&
 	git config i18n.commitencoding eucJP &&
 	git merge -F "$TEST_DIRECTORY/t3434/eucJP.txt" second &&
-- 
2.24.0.164.g78daf050de.dirty