Unable to checkout subversion source

When I try to `bzr branch https://svn.collab.net/repos/svn/trunk svn`, I get the bzr crash message after the progress indicator finishes with this trace:
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/commands.py", line 857, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/commands.py", line 797, in run_bzr
    ret = run(*run_argv)
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/commands.py", line 499, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/builtins.py", line 866, in run
    hardlink=hardlink, stacked=stacked)
  File "/Users/jon/.bazaar/plugins/svn/remote.py", line 66, in sprout
    return super(SvnRemoteAccess, self).sprout(*args, **kwargs)
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/bzrdir.py", line 1086, in sprout
    result_repo.fetch(source_repository, revision_id=revision_id)
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/repository.py", line 975, in fetch
    find_ghosts=find_ghosts)
  File "/Users/jon/.bazaar/plugins/svn/fetch.py", line 825, in fetch
    self._fetch_switch(self.source.transport.get_svn_repos_root(), needed, pb)
  File "/Users/jon/.bazaar/plugins/svn/fetch.py", line 755, in _fetch_switch
    editor = RevisionBuildEditor(self.source, self.target, revid, parent_inv, revmeta)
  File "/Users/jon/.bazaar/plugins/svn/fetch.py", line 405, in __init__
    assert prev_inventory.root is None or self.inventory.root.revision == prev_inventory.root.revision
AssertionError

And, predictably, I also get a nonfunctioning branch. This is after installing using Tim Dysinger's script to install bzr-svn (copy+pasted from his blog).

If I compile neon, svn, and svn's swig-py bindings manually using their latest stable versions (and enabling openssl in neon), then I get a different error when I try to do anything that loads bzr-svn (including simply `python ~/.bazaar/plugins/svn/__init__.py`). This is from my .bzr.log:
0.327 looking for plugins in /Users/jon/Library/Python/2.5/site-packages/bzr-1.5-py2.5-macosx-10.5-i386.egg/bzrlib/plugins
0.339 looking for plugins in /Library/Python/2.5/site-packages/bzrlib/plugins
0.401 encoding stdout as sys.stdout encoding 'UTF-8'
0.409 return code 0

0.743 encoding stdout as sys.stdout encoding 'UTF-8'
0.745 bzr arguments: [u'plugins']
0.745 looking for plugins in /Users/jon/.bazaar/plugins
1.076 bzr-svn: using Subversion 1.6.0 (-dev)
[10144] 2008-08-09 13:58:39.182 WARNING: Unable to load plugin 'svn' from '/Users/jon/.bazaar/plugins'
1.087 Traceback (most recent call last):
  File "/Users/jon/Library/Python/2.5/site-packages/bzr-1.5-py2.5-macosx-10.5-i386.egg/bzrlib/plugin.py", line 208, in load_from_dir
    exec "import bzrlib.plugins.%s" % name in {}
  File "<string>", line 1, in <module>
  File "/Users/jon/.bazaar/plugins/svn/__init__.py", line 158, in <module>
    log.properties_handler_registry.register_lazy("subversion",
AttributeError: 'module' object has no attribute 'properties_handler_registry'

Info on how to fix either would be fine. I just want a working bzr-svn on OSX 10.5.4 :)

My bazaar's `bzr version`:
  Python interpreter: /System/Library/Frameworks/Python.framework/Versions/2.5/Resources/Python.app/Contents/MacOS/Python 2.5.1
  Python standard library: /System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5
  bzrlib: /Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib
  Bazaar configuration: /Users/jon/.bazaar
  Bazaar log file: /Users/jon/.bzr.log
My bazaar's plugins:
  fastimport /Users/jon/.bazaar/plugins/fastimport [unknown]
  launchpad /Users/jon/Library/Python/2.5/site-packages/bzr-1.6rc1-py2.5-macosx-10.5-i386.egg/bzrlib/plugins/launchpad [unknown]
  svn /Users/jon/.bazaar/plugins/svn [0.4.11rc1]
My subversion:
  svn, version 1.6.0 (dev build)
My OS from `sysctl kern.version`:
  kern.version: Darwin Kernel Version 9.4.0: Mon Jun 9 19:30:53 PDT 2008; root:xnu-1228.5.20~1/RELEASE_I386
  (which is OSX 10.5.4)