It looks you fixed it in the changeset below. Closing.
user: Bryan O'Sullivan <firstname.lastname@example.org>
date: Mon May 14 01:13:07 2012 +0200
files: hgsubversion/svnwrap/svn_swig_wrapper.py tests/fixtures/addspecial.sh tests/fixtures/addspecial.svndump
canonicalize svn paths even more awesomely
It turns out that SVN has bizarre path canonicalization rules that
are sort of close to what urllib.quote does, but different in
peculiar ways, and 1.7 suddenly cares deeply about canonicality.
For instance, space (' ') maps to %20, but '~' stays unchanged
instead of turning into %7e.
Along with its new policy of frequent beatings administered to users
of its bindings, SVN 1.7 introduces a function that idempotently
canonicalizes URIs, which I found sort of by accident, because
that's how you learn about SVN API changes.
Older versions of SVN are less anal, so urllib.quote continues to
work fine for them.