suspected path too long gives bzr: ERROR: [Errno 2] No such file or directory:

Some months ago I updated from Windows 2.5.1 standalone install to 2.6b1 standalone install to get around a bug which caused occasional intractable issues. I forget the bug, but 2.6b1 solved it.

Anyway 2.6b1 has been working well, we have been creating branches, editing, merging, pushing, pulling as you do with little problem.

Alas last couple of days I have come across a repo that I cannot branch with 2.6b1 (although have not reinstalled 2.5.1 to check it works).

I suspect combined path and filename length limits may have been exceeded somewhere (just a hunch, I don't have the skills or experience to be confident of that).

I would like to know whether it is indeed likely to be a path length issue (so I can take action accordingly) or if it is likely something else (a bug?) is going on. And might 2.5.1 perform better in this situation?

If I run check -v, nothing untoward is reported.

Here is the error message that branching produces.

Run command: bzr branch "C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/trunk"...
bzr: ERROR: [Errno 2] No such file or directory: u'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/t/.bzr/checkout/limbo/new-18/Sketches/ELevation sketches/TMNDrawingSketchSalisburyUndergroundElev270/TMNDrawingSketchSalisburyUndergroundElev270-1.png'

If I hunt around for the offending file, i find it's combined path and name length is about 249 characters.

Here is a part of the bzr.log traceback.
Sat 2014-12-20 07:44:33 +1300
0.171 bazaar version: 2.6b1
0.187 bzr arguments: [u'qsubprocess', u'--bencode', u'l6:branch115:C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/trunk111:C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/t18:--use-existing-dire']
0.187 looking for plugins in C:/Documents and Settings/Bruce/Application Data/bazaar/2.0/plugins
0.187 looking for plugins in C:/Program Files/Bazaar/plugins
0.281 encoding stdout as osutils.get_user_encoding() 'cp1252'
0.515 bazaar version: 2.6b1
0.515 bzr arguments: [u'branch', u'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/trunk', u'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/t', u'--use-existing-dir']
0.515 encoding stdout as osutils.get_user_encoding() 'cp1252'
0.578 opening working tree 'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/trunk'
0.625 opening working tree 'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/trunk'
0.703 Using fetch logic to copy between CHKInventoryRepository('file:///C:/Documents%20and%20Settings/Bruce/My%20Documents/Bruce/Outdoor/Cave/Therion%20Data%20and%20Notes/th_FloraCaveSystemData/trunk/.bzr/repository/')(RepositoryFormat2a()) and CHKInventoryRepository('file:///C:/Documents%20and%20Settings/Bruce/My%20Documents/Bruce/Outdoor/Cave/Therion%20Data%20and%20Notes/th_FloraCaveSystemData/.bzr/repository/')(RepositoryFormat2a())
0.703 fetching: <SearchResult search:(set(['<email address hidden>']), ['<email address hidden>', '<email address hidden>', '<email address hidden>', '<email address hidden>', '<email address hidden>', ...], 0)>
0.703 creating branch <bzrlib.branch.BzrBranchFormat7 object at 0x01525E30> in file:///C:/Documents%20and%20Settings/Bruce/My%20Documents/Bruce/Outdoor/Cave/Therion%20Data%20and%20Notes/th_FloraCaveSystemData/t/
0.734 bzr-colo: setting nick from hook
0.781 created new branch BzrBranch7(file:///C:/Documents%20and%20Settings/Bruce/My%20Documents/Bruce/Outdoor/Cave/Therion%20Data%20and%20Notes/th_FloraCaveSystemData/t/)
0.796 opening working tree 'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/t'
3.125 Transferred: 0kB (0.0kB/s r:0kB w:0kB)
3.125 Transferred: 0kB (0.0kB/s r:0kB w:0kB)
3.125 Traceback (most recent call last):
  File "bzrlib\commands.pyo", line 930, in exception_to_return_code
  File "bzrlib\commands.pyo", line 1141, in run_bzr
  File "bzrlib\commands.pyo", line 673, in run_argv_aliases
  File "bzrlib\commands.pyo", line 697, 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 826, in run
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\subprocess.py", line 1011, in run_subprocess_command
  File "bzrlib\commands.pyo", line 1141, in run_bzr
  File "bzrlib\commands.pyo", line 673, in run_argv_aliases
  File "bzrlib\commands.pyo", line 697, 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 1489, in run
  File "bzrlib\bzrdir.pyo", line 366, in sprout
  File "bzrlib\cleanup.pyo", line 132, in run
  File "bzrlib\cleanup.pyo", line 166, in _do_with_cleanups
  File "bzrlib\bzrdir.pyo", line 434, in _sprout
  File "bzrlib\bzrdir.pyo", line 906, in create_workingtree
  File "bzrlib\workingtree_4.pyo", line 1565, in initialize
  File "bzrlib\transform.pyo", line 2535, in build_tree
  File "bzrlib\transform.pyo", line 2634, in _build_tree
  File "bzrlib\transform.pyo", line 2706, in _create_files
  File "bzrlib\transform.pyo", line 1315, in create_file
IOError: [Errno 2] No such file or directory: u'C:/Documents and Settings/Bruce/My Documents/Bruce/Outdoor/Cave/Therion Data and Notes/th_FloraCaveSystemData/t/.bzr/checkout/limbo/new-18/Sketches/ELevation sketches/TMNDrawingSketchSalisburyUndergroundElev270/TMNDrawingSketchSalisburyUndergroundElev270-1.png'

Here is mys system version info reported by Bazaar.

C:\Documents and Settings\Bruce\My Documents\Bruce\Outdoor\Cave\Therion Data and Notes\th_FloraCaveSystemData\Bruce02Branch\TeManaNuiCave\Sketches\ELevation sketches\TMNDrawingSketch09NileStreamExtElevEXT\TMNDrawingSketch09NileStreamExtElevEXT-1.png