After some more research, and a lot of help from #debian-devel (many thanks to Kibi and lamby), it appears that binary packages built from source end up with different contents depending on whether or not python-setuptools is installed.
I'll Build-Conflict on that package, which should solve it. Cheers, --Seb -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]