FWIW, we (JRuby) would appreciate if whatever change is made gets backported to 1.9.3, since we're running 1.9.3 test suite as part of our normal dev process.
This issue was solved with changeset r34750.
Charles, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.
Yui: Thank you. I will be adding this to our suite and excluding anything that fails. I won't worry too much about it since our iconv is implemented atop Java NIO Charset API.