The addError() handler is called outside of an actual exception handler so sys.exc_info() doesn't actually return an exception. This means that traceback.print_exc() doesn't know what to print. Instead we need to use traceback.print_exception() with the err object we've been given.
Cc'ing the maintainers listed in the readme along with Changqing Li as discussed during the Yocto Project call on Tuesday.
Could you confirm who's maintaining patchtest these days and update the readme? I've got a few ideas for enhancements and I may be able to assist with maintaining these repositories after the new year but I'd like to get these initial changes in first.