Rob pointed me to this bug when I told him about this:

stewart@willster:~/drizzle$ bzr branch lp:~eday/drizzle/eday-dev
bzr: ERROR: bzrlib.errors.ErrorFromSmartServer: Error received from smart server: ('NoSuchRevision',)

Traceback (most recent call last):
  File "/home/stewart/lib/python/bzrlib/commands.py", line 727, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/home/stewart/lib/python/bzrlib/commands.py", line 922, in run_bzr
    ret = run(*run_argv)
  File "/home/stewart/lib/python/bzrlib/commands.py", line 559, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/stewart/lib/python/bzrlib/builtins.py", line 1122, in run
    source_branch=br_from)
  File "/home/stewart/lib/python/bzrlib/bzrdir.py", line 1142, in sprout
    result_repo.fetch(source_repository, revision_id=revision_id)
  File "/home/stewart/lib/python/bzrlib/repository.py", line 1493, in fetch
    find_ghosts=find_ghosts, fetch_spec=fetch_spec)
  File "/home/stewart/lib/python/bzrlib/decorators.py", line 192, in write_locked
    result = unbound(self, *args, **kwargs)
  File "/home/stewart/lib/python/bzrlib/repository.py", line 3057, in fetch
    pb=pb, find_ghosts=find_ghosts)
  File "/home/stewart/lib/python/bzrlib/fetch.py", line 84, in __init__
    self.__fetch()
  File "/home/stewart/lib/python/bzrlib/fetch.py", line 110, in __fetch
    self._fetch_everything_for_search(search)
  File "/home/stewart/lib/python/bzrlib/fetch.py", line 138, in _fetch_everything_for_search
    stream, from_format, [])
  File "/home/stewart/lib/python/bzrlib/repository.py", line 3926, in insert_stream
    return self._locked_insert_stream(stream, src_format)
  File "/home/stewart/lib/python/bzrlib/repository.py", line 3954, in _locked_insert_stream
    for substream_type, substream in stream:
  File "/home/stewart/lib/python/bzrlib/remote.py", line 1734, in missing_parents_chain
    stream = self._get_stream(source, search)
  File "/home/stewart/lib/python/bzrlib/remote.py", line 1706, in _get_stream
    (path, self.to_format.network_name()), search_bytes)
  File "/home/stewart/lib/python/bzrlib/remote.py", line 71, in _call_with_body_bytes_expecting_body
    self._translate_error(err, **err_context)
  File "/home/stewart/lib/python/bzrlib/remote.py", line 688, in _translate_error
    self.bzrdir._translate_error(err, repository=self, **context)
  File "/home/stewart/lib/python/bzrlib/remote.py", line 129, in _translate_error
    _translate_error(err, bzrdir=self, **context)
  File "/home/stewart/lib/python/bzrlib/remote.py", line 2497, in _translate_error
    raise NoSuchRevision(find('branch'), err.error_args[0])
  File "/home/stewart/lib/python/bzrlib/remote.py", line 2481, in find
    raise err
ErrorFromSmartServer: Error received from smart server: ('NoSuchRevision',)

bzr 1.15dev on python 2.5.2 (linux2)
arguments: ['/home/stewart/bin/bzr', 'branch', 'lp:~eday/drizzle/eday-dev']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_AU.UTF-8'
plugins:
  automv               /home/stewart/.bazaar/plugins/automv [unknown]
  bisect               /home/stewart/.bazaar/plugins/bisect [1.1.0.pre.0]
  bzrtools             /home/stewart/.bazaar/plugins/bzrtools [1.13]
  checkeol             /home/stewart/.bazaar/plugins/checkeol [1.2.1]
  diffstat             /home/stewart/.bazaar/plugins/diffstat [0.2]
  gtk                  /home/stewart/.bazaar/plugins/gtk [0.96.0.dev.1]
  launchpad            /home/stewart/lib/python/bzrlib/plugins/launchpad [unknown]
  lessdiff             /home/stewart/.bazaar/plugins/lessdiff [unknown]
  loom                 /home/stewart/.bazaar/plugins/loom [1.4dev]
  mysql_plugins        /home/stewart/.bazaar/plugins/mysql_plugins [0.4.2]
  netrc_credential_store /home/stewart/lib/python/bzrlib/plugins/netrc_credential_store [unknown]
  notification         /home/stewart/.bazaar/plugins/notification [unknown]
  rebase               /home/stewart/.bazaar/plugins/rebase [0.4.5dev]
  repopush             /home/stewart/.bazaar/plugins/repopush [1.1]
  search               /home/stewart/.bazaar/plugins/search [1.7dev]
  signing              /home/stewart/.bazaar/plugins/signing [unknown]
  stats                /home/stewart/.bazaar/plugins/stats [unknown]
*** 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.