Leon, this most likely is not a bug, not because what's stated in documentation, but because you're most likely not testing what you think you do. Here is the test that you should be doing:

>>> re.match(r'(<)?(\w+@\w+(?:\.\w+)+)(?(1)>|$)', '<user@host.com')
>>>

No match. If there is a different output in your setup, please provide both the output and the details of your system and Python installation.