MemoryError in pack.bytes_record during fetch of enormous repository

Binary package hint: bzr

When using sftp to check out my ginormous repository of PDFs (physics articles I need to keep synchronized between desktops, netbook, and n810), bzr eats all of my available RAM (gets up to 1.4-1.5GB) and then, of course, runs out of RAM and gets killed:

$ bzr branch sftp://<workstation>./home/<user>/Documents
/usr/lib/python2.6/dist-packages/Crypto/Hash/SHA.py:6: DeprecationWarning: the sha module is deprecated; use the hashlib module instead
  from sha import *
/usr/lib/python2.6/dist-packages/Crypto/Hash/MD5.py:6: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  from md5 import *
bzr: ERROR: exceptions.MemoryError:

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 896, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 842, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 542, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.6/dist-packages/bzrlib/builtins.py", line 1045, in run
    source_branch=br_from)
  File "/usr/lib/python2.6/dist-packages/bzrlib/bzrdir.py", line 1116, in sprout
    result_repo.fetch(source_repository, revision_id=revision_id)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 1118, in fetch
    find_ghosts=find_ghosts)
  File "/usr/lib/python2.6/dist-packages/bzrlib/decorators.py", line 192, in write_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 2985, in fetch
    return self._pack(self.source, self.target, revision_ids)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 2992, in _pack
    revision_ids).pack()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 655, in pack
    return self._create_pack_from_packs()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 809, in _create_pack_from_packs
    self._copy_text_texts()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 786, in _copy_text_texts
    self.new_pack.text_index, readv_group_iter, total_items))
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 900, in _copy_nodes_graph
    write_index, output_lines, pb, readv_group_iter, total_items):
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 944, in _do_copy_nodes_graph
    pos, size = writer.add_bytes_record(raw_data, names)
  File "/usr/lib/python2.6/dist-packages/bzrlib/pack.py", line 154, in add_bytes_record
    serialised_record = self._serialiser.bytes_record(bytes, names)
  File "/usr/lib/python2.6/dist-packages/bzrlib/pack.py", line 105, in bytes_record
    return ''.join(byte_sections)
MemoryError

bzr 1.12 on python 2.6.1 (linux2)
arguments: ['/usr/bin/bzr', 'branch', 'sftp://<workstation>/home/<user>/Documents']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_US.UTF-8'
plugins:
  avahi /usr/lib/python2.6/dist-packages/bzrlib/plugins/avahi [0.3dev]
  builddeb /usr/lib/python2.6/dist-packages/bzrlib/plugins/builddeb [2.1dev]
  bzrtools /usr/lib/python2.6/dist-packages/bzrlib/plugins/bzrtools [1.12]
  dbus /usr/lib/python2.6/dist-packages/bzrlib/plugins/dbus [unknown]
  gtk /usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk [0.95.0.final.1]
  launchpad /usr/lib/python2.6/dist-packages/bzrlib/plugins/launchpad [unknown]
  loom /usr/lib/python2.6/dist-packages/bzrlib/plugins/loom [1.4dev]
  netrc_credential_store /usr/lib/python2.6/dist-packages/bzrlib/plugins/netrc_credential_store [unknown]
  rebase /usr/lib/python2.6/dist-packages/bzrlib/plugins/rebase [0.4.2]
  search /usr/lib/python2.6/dist-packages/bzrlib/plugins/search [1.7dev]
  stats /usr/lib/python2.6/dist-packages/bzrlib/plugins/stats [unknown]
  svn /usr/lib/python2.6/dist-packages/bzrlib/plugins/svn [0.5]
*** 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.

This occurred while it was "Adding file contents"

This occurs both when I do a lightweight checkout (bzr checkout --lightweight) and when doing a branch (bzr branch). I'd much prefer the lightweight checkout; then I only need rev history in one location and don't have to duplicate the files all over.