bzr pull crashes with exceptions.AttributeError: 'NoneType' object has no attribute 'as_dict' after system upgrade

On a debian squeeze system running 2.6.32-trunk-686 #1 SMP Sun Jan 10 06:32:16 UTC 2010 i686 GNU/Linux
After upgrading a couple of packages (among which wpasupplicant) did a bzr pull:

Thu 2010-03-11 06:38:03 +0100
0.768 bazaar version: 2.1.0
0.768 bzr arguments: [u'pull']
1.067 looking for plugins in /home/berni/.bazaar/plugins
1.068 looking for plugins in /usr/lib/python2.5/site-packages/bzrlib/plugins
3.003 encoding stdout as sys.stdout encoding 'UTF-8'
4.110 opening working tree '/home/berni/prj/tools/simplon-tool'
5.354 ssh implementation is OpenSSH
9.944 Using fetch logic to copy between KnitPackRepository('sftp://odie.dynalias.net/home/berni/prj/tools/simplon-tool/.bzr/repository/')(<RepositoryFormatKnitPack1>) and KnitPackRepository('file:///home/berni/prj/tools/simplon-tool/.bzr/repository/')(<RepositoryFormatKnitPack1>)
9.944 fetch up to rev {bjoss@chpcxp-bjoss-20100310163317-37a77zi3govxr1rn}

.. but the system froze (including window manager) before bzr pull was finished.
Then I rebooted the netbook, by pressing the on/off button for >10s as the system was not responding to keyboard nor mouse.
After reboot I now get bzr pull to crash with the following log:

Thu 2010-03-11 06:46:29 +0100
0.550 bazaar version: 2.1.0
0.550 bzr arguments: [u'pull']
0.712 looking for plugins in /home/berni/.bazaar/plugins
0.713 looking for plugins in /usr/lib/python2.5/site-packages/bzrlib/plugins
1.782 encoding stdout as sys.stdout encoding 'UTF-8'
2.310 opening working tree '/home/berni/prj/tools/simplon-tool'
3.077 ssh implementation is OpenSSH
3.962 Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 853, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 1055, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 661, in run_argv_aliases
    return self.run_direct(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 665, in run_direct
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/cleanup.py", line 122, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/cleanup.py", line 156, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 1004, in run
    branch_to.lock_write()
  File "/usr/lib/python2.5/site-packages/bzrlib/branch.py", line 2144, in lock_write
    return self.control_files.lock_write(token=token)
  File "/usr/lib/python2.5/site-packages/bzrlib/lockable_files.py", line 193, in lock_write
    token_from_lock = self._lock.lock_write(token=token)
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 594, in lock_write
    return self.wait_lock()
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 525, in wait_lock
    new_info = self.peek()
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 438, in peek
    info = self._read_info_file(self._held_info_path)
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 428, in _read_info_file
    return self._parse_info(self.transport.get_bytes(path))
  File "/usr/lib/python2.5/site-packages/bzrlib/lockdir.py", line 463, in _parse_info
    return rio.read_stanza(osutils.split_lines(info_bytes)).as_dict()
AttributeError: 'NoneType' object has no attribute 'as_dict'

3.987 couldn't find apport bug-reporting library: No module named apport
4.010 Transferred: 0KiB (0.4K/s r:0K w:0K)
4.011 return code 4

bzr pull crashes consistentely, as above, while bzr status and missing both work fine.