For the record, I've got subversion 1.6.12-3 from extras-devel installed in my N900.

$ svn --version
svn, version 1.6.12 (r955767)
compiled Jul 7 2010, 19:50:52

$ apt-cache show subversion | grep Maintainer
Maintainer: unknown <sebastien.lelong@gmail.com>

I don't think I've ever actually used it on my N900 before now, but I've just tried it, and I can svn co a private repository over svn+ssh, then run svn up in it. It works for me, no segfaults.

It would be useful if you could tell the world how to reproduce the problem: what svn command to run in a checkout of what (public) repository, using which protocol.