F5/Refresh causes internal error

[David Roberts]

WinXP, bzr-2.1.0rc1, explorer 1.0.0dev [r395]

Start bzr-explorer so that it defaults to displaying Welcome screen. Press F5/Refresh. Results in this error -

bzr: ERROR: exceptions.AttributeError: 'NoneType' object has no attribute 'lock_read'

Traceback (most recent call last):
  File "C:/Added Program Files/Bazaar/plugins\explorer\lib\explorer.py", line 1514, in do_refresh
  File "C:/Added Program Files/Bazaar/plugins\explorer\lib\wt_browser.py", line 79, in refresh
  File "C:/Added Program Files/Bazaar/plugins\explorer\lib\wt_browser.py", line 397, in refresh
  File "C:/Added Program Files/Bazaar/plugins\qbzr\lib\treewidget.py", line 1460, in refresh
AttributeError: 'NoneType' object has no attribute 'lock_read'

bzr 2.1.0rc1 on python 2.5.4 (win32)
arguments: ['bzr', 'explore']
encoding: 'cp1252', fsenc: 'mbcs', lang: None
plugins:
  bzrtools C:\Added Program Files\Bazaar\plugins\bzrtools [2.1.0b1]
  colo C:\Added Program Files\Bazaar\plugins\colo [0.0.2dev]
  explorer C:\Added Program Files\Bazaar\plugins\explorer [1.0.0dev]
  extmerge C:\Added Program Files\Bazaar\plugins\extmerge [unknown]
  launchpad C:\Added Program Files\Bazaar\plugins\launchpad [2.1.0rc1]
  netrc_credential_store C:\Added Program Files\Bazaar\plugins\netrc_credential_store [2.1.0rc1]
  qbzr C:\Added Program Files\Bazaar\plugins\qbzr [0.18.0]
  rebase C:\Added Program Files\Bazaar\plugins\rebase [0.5.5]
  svn C:\Added Program Files\Bazaar\plugins\svn [1.0.1]
  upload C:\Added Program Files\Bazaar\plugins\upload [1.0.0dev]
  xmloutput C:\Added Program Files\Bazaar\plugins\xmloutput [0.8.5]