This issue was solved with changeset r42687.
Kazuhiro, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.
ChangeLog: convert with `iconv -t us-ascii//translit'. [Bug #8819]
I would suggest to change an encoding of Changelog to UTF-8.
Please remember why we credit contributor's name in Changelog.
It is for thanking them. Incorrect name is not a polite way.....