listing.py: Fixed regression crash when viewing unversioned directories or files, due to silly code raising pysvn.ClientError (not an instance of it). Now raise a special exception UnversionedDir, which is checked properly.
<py:for each="segment in paths">/<a href="${segment['href_path']}" title="Navigate to ${segment['nav_path']}">${segment['path']}</a></py:for> (Subversion diff)