failure when starting builtin diff utility

[Jeff Hill]

bzr: ERROR: exceptions.IndexError: pop from empty list

Traceback (most recent call last):
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\trace.py", line 365, in reports_exception_decorate
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\diffwindow.py", line 365, in initial_load
  File "bzrlib\cleanup.pyo", line 132, in run
  File "bzrlib\cleanup.pyo", line 166, in _do_with_cleanups
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\diffwindow.py", line 379, in _initial_load
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\diffwindow.py", line 473, in load_diff
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\diffview.py", line 669, in append_diff
  File "C:/Program Files (x86)/Bazaar/plugins\qbzr\lib\diffview.py", line 617, in insertIxsWithChangesHighlighted
IndexError: pop from empty list

bzr 2.5.1 on python 2.6.6 (win32)
arguments: ['C:\\Program Files (x86)\\Bazaar\\bzrw.exe', 'qcommit', '--ui-mode']
encoding: 'cp1252', fsenc: 'mbcs', lang: None
plugins:
  bzrtools C:\Program Files (x86)\Bazaar\plugins\bzrtools [2.5.0]
  changelog_merge C:\Program Files (x86)\Bazaar\plugins\changelog_merge [2.5.1]
  colo C:\Program Files (x86)\Bazaar\plugins\colo [0.4.0]
  explorer C:\Program Files (x86)\Bazaar\plugins\explorer [1.3.0]
  fastimport C:\Program Files (x86)\Bazaar\plugins\fastimport [0.14.0dev]
  git C:\Program Files (x86)\Bazaar\plugins\git [0.6.8]
  launchpad C:\Program Files (x86)\Bazaar\plugins\launchpad [2.5.1]
  loom C:\Program Files (x86)\Bazaar\plugins\loom [2.3.0dev]
  netrc_credential_store C:\Program Files (x86)\Bazaar\plugins\netrc_credential_store [2.5.1]
  news_merge C:\Program Files (x86)\Bazaar\plugins\news_merge [2.5.1]
  pipeline C:\Program Files (x86)\Bazaar\plugins\pipeline [1.4.0]
  qbzr C:\Program Files (x86)\Bazaar\plugins\qbzr [0.22.3]
  rewrite C:\Program Files (x86)\Bazaar\plugins\rewrite [0.6.4dev]
  svn C:\Program Files (x86)\Bazaar\plugins\svn [1.2.2]
  upload C:\Program Files (x86)\Bazaar\plugins\upload [1.2.0dev]
  xmloutput C:\Program Files (x86)\Bazaar\plugins\xmloutput [0.8.8]