messages of mailman's command are corrupted in Japanese

Issue

When exec '/usr/lib/mailman/bin/rmlist -a test', output messages are corrupted in Japanese.

# /usr/lib/mailman/bin/rmlist -a test
test というリストはありません. 残された保存書庫を削除します.
test ������篆���後昆 は /var/lib/mailman/archives/private/test に見つかりません
test ������篆���後昆 は /var/lib/mailman/archives/private/test.mbox に見つかりません
test ���篆���後昆 は /var/lib/mailman/archives/public/test に見つかりません
test ���篆���後昆 は /var/lib/mailman/archives/public/test.mbox に見つかりません

In LANG=C, the following result:

LANG=C /usr/lib/mailman/bin/rmlist -a test
No such list: test.  Removing its residual archives.
test private archives not found as /var/lib/mailman/archives/private/test
test private archives not found as /var/lib/mailman/archives/private/test.mbox
test public archives not found as /var/lib/mailman/archives/public/test
test public archives not found as /var/lib/mailman/archives/public/test.mbox