The url in the latest ebuild points to http://twistedmatrix.com/Releases/Web/13.2/TwistedWeb/TwistedWeb-13.2.0.tar.bz2 while the correct one is http://twistedmatrix.com/Releases/Web/13.2/TwistedWeb-13.2.0.tar.bz2
*** Bug 498596 has been marked as a duplicate of this bug. ***
Fixed. Thanks for reporting!