update failure - is not locked

saw this failure

bzr: ERROR: bzrlib.errors.ObjectNotLocked: <WorkingTree6 of C:/hill/epicsInBazaar/rebased-atomics/trunk> is not locked

Traceback (most recent call last):
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\app_runner.py", line 96, in do_finished
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\explorer.py", line 1116, in conditional_refresh
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\explorer.py", line 1764, in do_refresh
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\explorer.py", line 679, in changed_view
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\wt_browser.py", line 65, in set_tree
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\wt_browser.py", line 469, in set_tree
  File "C:/Program Files (x86)/Bazaar/plugins\explorer\lib\wt_browser.py", line 631, in set_tree
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\treewidget.py", line 1462, in set_tree
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\treewidget.py", line 422, in set_tree
  File "bzrlib\tree.pyo", line 101, in iter_changes
  File "bzrlib\workingtree_4.pyo", line 2180, in iter_changes
  File "bzrlib\workingtree_4.pyo", line 221, in current_dirstate
  File "bzrlib\workingtree_4.pyo", line 892, in _must_be_locked
ObjectNotLocked: <WorkingTree6 of C:/hill/epicsInBazaar/rebased-atomics/trunk> is not locked

bzr 2.4b5 on python 2.6.6 (win32)
arguments: ['C:\\Program Files (x86)\\Bazaar\\bzrw.exe', 'explorer']
encoding: 'cp1252', fsenc: 'mbcs', lang: None
plugins:
  bzrtools C:\Program Files (x86)\Bazaar\plugins\bzrtools [2.4.0]
  changelog_merge C:\Program Files (x86)\Bazaar\plugins\changelog_merge [2.4b5]
  colo C:\Program Files (x86)\Bazaar\plugins\colo [0.3.1dev]
  explorer C:\Program Files (x86)\Bazaar\plugins\explorer [1.1.4]
  fastimport C:\Program Files (x86)\Bazaar\plugins\fastimport [0.11.0dev]
  launchpad C:\Program Files (x86)\Bazaar\plugins\launchpad [2.4b5]
  loom C:\Program Files (x86)\Bazaar\plugins\loom [2.2.1dev]
  netrc_credential_store C:\Program Files (x86)\Bazaar\plugins\netrc_credential_store [2.4b5]
  news_merge C:\Program Files (x86)\Bazaar\plugins\news_merge [2.4b5]
  pipeline C:\Program Files (x86)\Bazaar\plugins\pipeline [1.1.0]
  qbzr C:\Program Files (x86)\Bazaar\plugins\qbzr [0.21b1]
  rewrite C:\Program Files (x86)\Bazaar\plugins\rewrite [0.7.0dev]
  svn C:\Program Files (x86)\Bazaar\plugins\svn [1.1.0dev]
  upload C:\Program Files (x86)\Bazaar\plugins\upload [1.0.1dev]
  xmloutput C:\Program Files (x86)\Bazaar\plugins\xmloutput [0.8.7]