Got list instead of iterator, causes import failure

Seems like it should be a trivial fix. This is affecting the import of python-unittest2:

Traceback (most recent call last):
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/scripts/code-import-worker.py", line 82, in <module>
    sys.exit(script.main())
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/scripts/code-import-worker.py", line 77, in main
    return import_worker.run()
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/lib/lp/codehosting/codeimport/worker.py", line 480, in run
    return self._doImport()
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/lib/lp/codehosting/codeimport/worker.py", line 625, in _doImport
    inter_branch.fetch(limit=self.getRevisionLimit())
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/branch.py", line 465, in fetch
    inter.fetch(revision_id=stop_revision, limit=limit)
  File "<string>", line 4, in fetch_write_locked
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/fetch.py", line 752, in fetch
    self.addchangegroup(cg, mapping, limit=limit)
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/fetch.py", line 617, in addchangegroup
    self.target.texts.insert_record_stream(texts)
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/eggs/bzr-2.3.3-py2.6-linux-x86_64.egg/bzrlib/groupcompress.py", line 1617, in insert_record_stream
    for _ in self._insert_record_stream(stream, random_id=False):
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/eggs/bzr-2.3.3-py2.6-linux-x86_64.egg/bzrlib/groupcompress.py", line 1683, in _insert_record_stream
    for record in stream:
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/fetch.py", line 414, in _unpack_texts
    itertextchunks, get_text):
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/parsers.py", line 151, in unpack_chunk_iter
    textbase = lookup_base(base)
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/fetch.py", line 410, in get_text
    return self._target_overlay.get_text_by_path_and_node(path, node)
  File "/srv/importd.launchpad.net/production/launchpad-rev-13687/bzrplugins/optional/hg/overlay.py", line 112, in get_text_by_path_and_node
    (fileid, revid) = self.idmap.lookup_text_by_path_and_node(path, node).next()
AttributeError: 'list' object has no attribute 'next'