On musl libc, ISO-2022-JP encoder is too eager to switch back to
1 byte encoding, musl's iconv always switch back after every combining
character. Comparing glibc and musl's output for this command
$ sed q t/t3900/ISO-2022-JP.txt| iconv -f ISO-2022-JP -t utf-8 |
	iconv -f utf-8 -t ISO-2022-JP | xxd

glibc:
00000000: 1b24 4224 4f24 6c24 5224 5b24 551b 2842  .$B$O$l$R$[$U.(B
00000010: 0a                                       .

musl:
00000000: 1b24 4224 4f1b 2842 1b24 4224 6c1b 2842  .$B$O.(B.$B$l.(B
00000010: 1b24 4224 521b 2842 1b24 4224 5b1b 2842  .$B$R.(B.$B$[.(B
00000020: 1b24 4224 551b 2842 0a                   .$B$U.(B.

Although musl iconv's output isn't optimal, it's still correct.

From commit 7d509878b8, ("pretty.c: format string with truncate respects
logOutputEncoding", 2014-05-21), we're encoding the message to utf-8
first, then format it and convert the message to the actual output
encoding on git commit --squash.

Thus, t3900::test_commit_autosquash_flags is failing on musl libc.

Reencode to utf-8 before arranging rebase's todo list.

By doing this, we also remove a breakage noticed by a test added in the
previous commit.

Signed-off-by: Doan Tran Cong Danh <redacted>
---
 sequencer.c            | 2 +-
 t/t3900-i18n-commit.sh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 9d5964fd81..69430fe23f 100644
--- a/sequencer.c
+++ b/sequencer.c

@@ -5169,7 +5169,7 @@ int todo_list_rearrange_squash(struct todo_list *todo_list)
 		*commit_todo_item_at(&commit_todo, item->commit) = item;
 
 		parse_commit(item->commit);
-		commit_buffer = get_commit_buffer(item->commit, NULL);
+		commit_buffer = logmsg_reencode(item->commit, NULL, "UTF-8");
 		find_commit_subject(commit_buffer, &subject);
 		format_subject(&buf, subject, " ");
 		subject = subjects[i] = strbuf_detach(&buf, &subject_len);

diff --git a/t/t3900-i18n-commit.sh b/t/t3900-i18n-commit.sh
index dd56384b93..a518281b04 100755
--- a/t/t3900-i18n-commit.sh
+++ b/t/t3900-i18n-commit.sh

@@ -209,7 +209,7 @@ test_commit_autosquash_multi_encoding () {
 	old=$2
 	new=$3
 	msg=$4
-	test_expect_failure "commit --$flag into $old from $new" '
+	test_expect_success "commit --$flag into $old from $new" '
 		git checkout -b $flag-$old-$new C0 &&
 		git config i18n.commitencoding $old &&
 		echo $old >>F &&

-- 
2.24.0.8.g2e95ca57d2.dirty