gsub :: ArgumentError (invalid byte sequence in UTF-8)
===

This code uses the `Hpricot` gem to get HTML that contains UTF-8 characters.

    # <div>This is a test<a href="">测试</a></div>
    div[0].to_html.gsub(/test/, "")

When that is run, it spits out this error (pointing at gsub):

    ArgumentError (invalid byte sequence in UTF-8)

How can we fix this issue?