[Twisted-Python] weird spammy trac emails?

[exarkun at twistedmatrix.com]

On 02:34 pm, phil at bubblehouse.org wrote:
>Hey all,
>
>Have any of you gotten these weird spammy messages from trac? I'm
>getting change notifications on tickets I opened years ago, with no
>apparent info in it about what the change is except a spam URL.
>
>I've attached the ones I've received. I can't figure out how this
>would even be possible for a spammer to do; there must be some kind of
>exploit in trac....

The exploit is open registration.  I'm open to suggestions about how to 
deal with this problem.

Jean-Paul