Oh, hey, PEP 3127 actually asks for a better error message than "invalid token" for this case: http://www.python.org/dev/peps/pep-3127/#tokenizer-exception-handling

So here's a tentative patch to test the waters.  I still haven't figured out how to write tests for it (is Lib/test/test_tokenize.py the right place for that?), and I haven't manually tested it either, because building CPython tip fails for me with a strange link error about _PyTraceMalloc_Init/_PyTraceMalloc_Fini.

If there's some documentation I should read about submitting CPython patches, or some IRC channel I should join, please tell me!