bzr-svn, https subversion repo. and "different rich-root support"

I'm on a Mac (10.5.7).
BZR version:
Bazaar (bzr) 1.14.1
  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: /Library/Python/2.5/site-packages/bzrlib
  Bazaar configuration: /Users/eberry/.bazaar
  Bazaar log file: /Users/eberry/.bzr.log

Copyright 2005, 2006, 2007, 2008, 2009 Canonical Ltd.
http://bazaar-vcs.org/

bzr comes with ABSOLUTELY NO WARRANTY. bzr is free software, and
you may use, modify and redistribute it under the terms of the GNU
General Public License version 2 or later.

bzr-svn version (from bzr plugins):
svn 0.5.3

When I try to branch from my https subversion repository I get this message:
[572] bzr branch svn+https://[subversion]/bzr_svn/test/trunk remote
The svn+ syntax is deprecated, use https://[subversion]/bzr_svn/test/trunk instead.
bzr: ERROR: KnitPackRepository('file:///Users/eberry/development/projects/bzr_svn_test/.bzr/repository/')
is not compatible with
SvnRepository('svn+https://[subversion]/bzr_svn')
different rich-root support

I have to use svn+https, because using plain https results in a 401 authentication error.
bzr: ERROR: Invalid http response for https://[subversion]/bzr_svn/test/trunk/.bzr/branch-format: Unable to handle http code 401: Authorization Required

Any help would be greatly appreciated.

Thanks!