Got this same error just now using 2.1.1 (which I guess the creator of the patch was using) and again after installing 2.2.0
Transcript follows...

Run command: bzr merge "C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_RiwakaCaveSystemData/39-Mik...
bzr: ERROR: exceptions.IndexError: list index out of range

Traceback (most recent call last):
  File "bzrlib\commands.pyo", line 911, in exception_to_return_code
  File "bzrlib\commands.pyo", line 1111, in run_bzr
  File "bzrlib\commands.pyo", line 689, in run_argv_aliases
  File "bzrlib\commands.pyo", line 704, in run
  File "bzrlib\cleanup.pyo", line 135, in run_simple
  File "bzrlib\cleanup.pyo", line 165, in _do_with_cleanups
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\commands.py", line 767, in run
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\subprocess.py", line 869, in run_subprocess_command
  File "bzrlib\commands.pyo", line 1111, in run_bzr
  File "bzrlib\commands.pyo", line 689, in run_argv_aliases
  File "bzrlib\commands.pyo", line 704, in run
  File "bzrlib\cleanup.pyo", line 135, in run_simple
  File "bzrlib\cleanup.pyo", line 165, in _do_with_cleanups
  File "bzrlib\builtins.pyo", line 3843, in run
  File "bzrlib\merge.pyo", line 368, in from_mergeable
  File "bzrlib\merge_directive.pyo", line 278, in install_revisions
  File "bzrlib\bundle\serializer\v4.pyo", line 471, in install_revisions
  File "bzrlib\bundle\serializer\v4.pyo", line 539, in install
  File "bzrlib\bundle\serializer\v4.pyo", line 569, in _install_in_write_group
  File "bzrlib\bundle\serializer\v4.pyo", line 690, in _install_inventory_records
  File "bzrlib\multiparent.pyo", line 167, in to_lines
  File "bzrlib\multiparent.pyo", line 502, in get_line_list
  File "bzrlib\multiparent.pyo", line 512, in cache_version
  File "bzrlib\multiparent.pyo", line 661, in reconstruct_version
  File "bzrlib\multiparent.pyo", line 654, in _reconstruct
IndexError: list index out of range

bzr 2.2.0 on python 2.6.4 (Windows-XP-5.1.2600-SP3)
arguments: ['C:\\Program Files\\Bazaar\\bzr.exe', 'qsubprocess', '--bencode', 'l5:merge142:C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_RiwakaCaveSystemData/39-MikesCelebrationSeries.Patch11:--directory116:C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_RiwakaCaveSystemData/trunke']
encoding: 'cp1252', fsenc: 'mbcs', lang: None
plugins:
  bzrtools             C:\Program Files\Bazaar\plugins\bzrtools [2.2.0]
  colo                 C:\Program Files\Bazaar\plugins\colo [0.1.0]
  explorer             C:\Program Files\Bazaar\plugins\explorer [1.1b1]
  fastimport           C:\Program Files\Bazaar\plugins\fastimport [0.9.0dev]
  launchpad            C:\Program Files\Bazaar\plugins\launchpad [2.2.0]
  loom                 C:\Program Files\Bazaar\plugins\loom [2.2.1dev]
  netrc_credential_store C:\Program Files\Bazaar\plugins\netrc_credential_store [2.2.0]
  news_merge           C:\Program Files\Bazaar\plugins\news_merge [2.2.0]
  pipeline             C:\Program Files\Bazaar\plugins\pipeline [unknown]
  qbzr                 C:\Program Files\Bazaar\plugins\qbzr [0.19.0]
  rewrite              C:\Program Files\Bazaar\plugins\rewrite [0.6.0]
  svn                  C:\Program Files\Bazaar\plugins\svn [1.0.3]
  upload               C:\Program Files\Bazaar\plugins\upload [1.0.0dev]
  xmloutput            C:\Program Files\Bazaar\plugins\xmloutput [0.8.6]

*** Bazaar has encountered an internal error.  This probably indicates a
    bug in Bazaar.  You can help us fix it by filing a bug report at
        https://bugs.launchpad.net/bzr/+filebug
    including this traceback and a description of the problem.