UnboundLocalError after naive log command

I am completely new to version control - and struggling. My actions might look silly, but not as silly as the ones I removed from the list below!

Here's what I did, with summarised results, including traceback:

> cd L:\Bazaar\
> L:
> bzr whoami
Derek
> cd F:\My Documents\Visual Studio 2005\Projects VB\SysBak DEVELOPMENT\
> F:
> bzr init-repo --trees .
> bzr init-repo --no-trees "file:///X:/Derek's Temp Backups/SysBak REPOSITORY/bzr"
> bzr init "file:///X:/Derek's Temp Backups/SysBak REPOSITORY/bzr/SysBak"
> cd F:\My Documents\Visual Studio 2005\Projects VB\SysBak DEVELOPMENT\SysBak ORIGINAL\
> bzr checkout "file:///X:/Derek's Temp Backups/SysBak REPOSITORY/bzr/SysBak" "SysBak ORIGINAL"
> bzr --dry-run add
> bzr ignore *.resx
> bzr ignore *.user
> bzr ignore *.vbproj
> bzr ignore *.myapp
> bzr ignore *.Designer.*
> bzr ignore AssemblyInfo.vb
> bzr ignore Settings.settings
> bzr ignore *.vbproj.*
> bzr ignore *.exe
> bzr ignore *.pdb
> bzr ignore *.xml
> bzr ignore *.resources
> bzr ignore TempPE
> bzr add --dry-run
> bzr add
> bzr status
> bzr log OverlayWindow.vb
bzr: ERROR: Path unknown at end or start of revision range: OverlayWindow.vb
> bzr log SysBak\OverlayWindow.vb
bzr: ERROR: exceptions.UnboundLocalError: local variable 'next_keys' referenced before assignment

Traceback (most recent call last):
  File "bzrlib\commands.pyo", line 716, in exception_to_return_code
  File "bzrlib\commands.pyo", line 911, in run_bzr
  File "bzrlib\commands.pyo", line 547, in run_argv_aliases
  File "bzrlib\commands.pyo", line 926, in ignore_pipe
  File "bzrlib\builtins.pyo", line 2168, in run
  File "bzrlib\log.pyo", line 182, in show_log
  File "bzrlib\log.pyo", line 227, in _show_log
  File "bzrlib\log.pyo", line 317, in _create_log_revision_iterator
  File "bzrlib\log.pyo", line 972, in _filter_revisions_touching_file_id
UnboundLocalError: local variable 'next_keys' referenced before assignment

bzr 1.13 on python 2.5.2 (win32)
arguments: ['bzr', 'log', 'SysBak\\OverlayWindow.vb']
encoding: 'cp1252', fsenc: 'mbcs', lang: None
plugins:
  bzrtools L:\Bazaar\plugins\bzrtools [1.13]
  gtk C:\Documents and Settings\Derek\Application Data\bazaar\2.0\plugins\gtk [0.95
.0.final.1]
  launchpad L:\Bazaar\plugins\launchpad [unknown]
  netrc_credential_store L:\Bazaar\plugins\netrc_credential_store [unknown]
  qbzr L:\Bazaar\plugins\qbzr [0.9.8]
  svn L:\Bazaar\plugins\svn [0.5.3]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred.