Did subversion (client) ever run on a GNU/Hurd system? I found lots of subversion tools on Debian GNU/Hurd but not the client itself.
Because of missing build dependencies, there is currently no subversion package available for Debian GNU/Hurd.
It might very well be that you could have success building it `by hand'; perhaps you don't need the missing functionality to get the client built.
http://dept-info.labri.fr/~thibault/debian-hurd/ contains subversion packages, thanks to Samuel Thibault.