failing test case for filenames with a percent

Before I start working on a fix for this (unfortunately would have to be in the send module), do you think it's a valid test case?

I think it is because if you set the `href` attribute in a dom element in a browser to a URL with a pathname which has a percent sign in it, and the user clicks the link, the `%` is not escaped and the server should be able to figure out what to do.