Comment 5 for bug 327966

This brings up a possible source of the conflict.

Do you have "subversion" installed separately on your machine?

IIRC subversion supplies 2 versions of their libraries, one built against different versions of the apache runtime.

As such it would be possible that when trying to import subvertpy, it goes to load the subversion bindings, but is finding your other install, rather than the ones bundled with it. And since they conflict, it fails to load, which then causes bzr-svn to fail to load, and triggers this bug.