Comment 3 for bug 505987

We are getting passed a Unicode string holding a file-id.

I'm pretty sure it is just going through one of the QBzr dialogs, given the "get_diff_window_args" call, and it certainly looks like the file_id is passed down from 'id2path'. We *could* add a 'str(file_id)' or "file_id.encode('utf-8')" on our end, but we're pretty good about ensuring we only have 'str' file-ids internally. I'd rather have the qbzr code do the type checking.