merge exception bzr: ERROR: exceptions.IndexError: list index out of range

Trying to merge a routine patch sent from another user to my trunk. Not sure why this one should be any different to the many successful merges in the past. In the traceback below the file name;
MikesBranch02-1.patch11
seems to have an erroneous "11" appended, and similarly ;
trunke
has an erroneous "e" appended.

Any ideas?
Bruce

Run command: bzr merge "C:\Documents and Settings\Bruce\My Documents\Bruce\Outdoor\Cave\Therion Data and Notes\th_BulmerCaveSystemData\MikesB...
bzr: ERROR: exceptions.IndexError: list index out of range

Traceback (most recent call last):
  File "bzrlib\commands.pyo", line 920, in exception_to_return_code
  File "bzrlib\commands.pyo", line 1131, in run_bzr
  File "bzrlib\commands.pyo", line 673, in run_argv_aliases
  File "bzrlib\commands.pyo", line 695, in run
  File "bzrlib\cleanup.pyo", line 136, in run_simple
  File "bzrlib\cleanup.pyo", line 166, in _do_with_cleanups
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\commands.py", line 823, in run
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\subprocess.py", line 920, in run_subprocess_command
  File "bzrlib\commands.pyo", line 1131, in run_bzr
  File "bzrlib\commands.pyo", line 673, in run_argv_aliases
  File "bzrlib\commands.pyo", line 695, in run
  File "bzrlib\cleanup.pyo", line 136, in run_simple
  File "bzrlib\cleanup.pyo", line 166, in _do_with_cleanups
  File "bzrlib\builtins.pyo", line 4414, in run
  File "bzrlib\merge.pyo", line 381, in from_mergeable
  File "bzrlib\merge_directive.pyo", line 286, in install_revisions
  File "bzrlib\bundle\serializer\v4.pyo", line 474, in install_revisions
  File "bzrlib\bundle\serializer\v4.pyo", line 542, in install
  File "bzrlib\bundle\serializer\v4.pyo", line 572, in _install_in_write_group
  File "bzrlib\bundle\serializer\v4.pyo", line 693, in _install_inventory_records
  File "bzrlib\multiparent.pyo", line 170, in to_lines
  File "bzrlib\multiparent.pyo", line 513, in get_line_list
  File "bzrlib\multiparent.pyo", line 523, in cache_version
  File "bzrlib\multiparent.pyo", line 673, in reconstruct_version
  File "bzrlib\multiparent.pyo", line 666, in _reconstruct
IndexError: list index out of range

bzr 2.5.1 on python 2.6.6 (Windows-XP-5.1.2600-SP3)
arguments: ['C:\\Program Files\\Bazaar\\bzr.exe', 'qsubprocess', '--bencode',
    'l5:merge132:C:\\Documents and Settings\\Bruce\\My
    Documents\\Bruce\\Outdoor\\Cave\\Therion Data and Notes\\th_BulmerCaveSyst
    emData\\MikesBranch02-1.patch11:--directory116:C:/Documents and
    Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and
    Notes/th_BulmerCaveSystemData/trunke']
plugins: bzrtools[2.5.0], changelog_merge[2.5.1], colo[0.4.0],
    explorer[1.2.2], fastimport[0.14.0dev], git[0.6.8], launchpad[2.5.1],
    loom[2.3.0dev], netrc_credential_store[2.5.1], news_merge[2.5.1],
    pipeline[1.4.0], qbzr[0.22.3], rewrite[0.6.4dev], svn[1.2.2],
    upload[1.2.0dev], xmloutput[0.8.8]
encoding: 'cp1252', fsenc: 'mbcs', lang: None