bzr crash on shelving

bzr: ERROR: bzrlib.errors.MalformedTransform: Tree transform is malformed [('unversioned parent', 'new-4'), ('missing parent', 'new-4')]

Traceback (most recent call last):
  File "D:/Apps/Bazaar/plugins\qbzr\lib\widgets\shelve.py", line 715, in do_shelve
  File "bzrlib\shelf.pyo", line 382, in shelve_changes
  File "bzrlib\shelf.pyo", line 256, in transform
  File "bzrlib\transform.pyo", line 1730, in apply
  File "bzrlib\transform.pyo", line 554, in _check_malformed
MalformedTransform: Tree transform is malformed [('unversioned parent', 'new-4'), ('missing parent', 'new-4')]

bzr 2.5.1 on python 2.6.6 (win32)
arguments: ['D:\\Apps\\Bazaar\\bzrw.exe', 'qshelve', '--ui-mode']
encoding: 'cp1250', fsenc: 'mbcs', lang: None
plugins:
  bzrtools             D:\Apps\Bazaar\plugins\bzrtools [2.5.0]
  changelog_merge      D:\Apps\Bazaar\plugins\changelog_merge [2.5.1]
  colo                 D:\Apps\Bazaar\plugins\colo [0.4.0]
  explorer             D:\Apps\Bazaar\plugins\explorer [1.2.2]
  fastimport           D:\Apps\Bazaar\plugins\fastimport [0.14.0dev]
  git                  D:\Apps\Bazaar\plugins\git [0.6.8]
  launchpad            D:\Apps\Bazaar\plugins\launchpad [2.5.1]
  loom                 D:\Apps\Bazaar\plugins\loom [2.3.0dev]
  netrc_credential_store D:\Apps\Bazaar\plugins\netrc_credential_store [2.5.1]
  news_merge           D:\Apps\Bazaar\plugins\news_merge [2.5.1]
  pipeline             D:\Apps\Bazaar\plugins\pipeline [1.4.0]
  qbzr                 D:\Apps\Bazaar\plugins\qbzr [0.22.3]
  rewrite              D:\Apps\Bazaar\plugins\rewrite [0.6.4dev]
  svn                  D:\Apps\Bazaar\plugins\svn [1.2.2]
  upload               D:\Apps\Bazaar\plugins\upload [1.2.0dev]
  xmloutput            D:\Apps\Bazaar\plugins\xmloutput [0.8.8]