Eu tive problema semelhante no Ubuntu 12.04. Eu atualizei o subversion para o 1.7.5 usando o pacote WANdisco. Este pacote vincula o svn ao python2.6 e o Ubuntu 12.04 tem o python2.7.
Aqui está um script que resolveu o problema do meu lado:
mkdir /usr/lib/python2.7/dist-packages/libsvn
for f in /usr/lib/pyshared/python2.6/libsvn/*; do ln -s $f /usr/lib/python2.7/dist-packages/libsvn/; done
for f in /usr/share/pyshared/libsvn/*; do ln -s $f /usr/lib/python2.7/dist-packages/libsvn/; done
mkdir /usr/lib/python2.7/dist-packages/svn
for f in /usr/share/pyshared/svn/*; do ln -s $f /usr/lib/python2.7/dist-packages/svn/; done
mkdir /usr/lib/pyshared/python2.7/libsvn
for f in /usr/lib/pyshared/python2.6/libsvn/*; do ln -s $f /usr/lib/pyshared/python2.7/libsvn/; done
Atenciosamente Wojciech Dec