In Mercurial, filename is not UTF-8 but byte-string.
So it should be escaped to UTF-8-safe string before parsing as XML document.

NOTE: Mercurial's {|obfuscate} filter cannot be used here, because it treats
filename as encoded by HGENCODING.

Contributed by Yuya Nishihara.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4633 e93f8b46-1217-0410-a6f0-8f06a7374b81