SimpleXMLRPCRequestHandler.do_POST() writes the traceback in the HTTP header "X-traceback". But an HTTP header value is ASCII only, whereas a traceback can contain any character (eg. an non-ASCII character from a directory name for this issue).
A simple fix would be to use the ASCII charset with the backslashreplace error handler. Attached patch uses:
trace = str(trace.encode('ASCII', 'backslashreplace'), 'ASCII')
Is there an easier method to escape non-ASCII characters without double conversion (unicode->bytes and bytes->unicode)?