セキュリティfixが出たね。

1.8.6, 1.8.7, 1.8.8dev, 1.9.1, 1.9.2, 1.9.3dev
http://www.ruby-lang.org/ja/news/2011/02/18/fileutils-is-vulnerable-to-symlink-race-attacks/

1.8.6, 1.8.7, 1.8.8dev
http://www.ruby-lang.org/ja/news/2011/02/18/exception-methods-can-bypass-safe/