Comment 34 for bug 254035

so I had a very similar problem today, on the mac

it turned out that easy_install had at some point installed twisted into /Library, and somehow tahoe (specifcally make test) was pulling in twisted from /System/Library (the apple supplied version) which wound up barfing on an error it got whilst cross-importing bits of twisted from out of /Library. I removed the twisted egg etc from /Library, but also needed to add

 "--site-dirs /System/Library/Frameworks/Python.framework/Versions/2.5/Extras/lib/python"

to the build args in order to get tahoe's build to not try and install a different version of twisted and instead use the extant system one. I'll submit a patch to that end shortly.