Code review comment for lp:~mbp/bzr/remove-controlfiles

this causes at least one failure in

  File "/usr/lib/python2.6/dist-packages/testtools/runtest.py", line 128, in _run_user
    return fn(*args)
  File "/usr/lib/python2.6/dist-packages/testtools/testcase.py", line 368, in _run_test_method
    testMethod()
  File "/home/mbp/bzr/remove-controlfiles/bzrlib/tests/per_branch/test_locking.py", line 64, in test_01_lock_read
    b = self.get_instrumented_branch()
  File "/home/mbp/bzr/remove-controlfiles/bzrlib/tests/per_branch/test_locking.py", line 42, in get_instrumented_branch
    bcf = b.control_files
  File "/home/mbp/bzr/remove-controlfiles/bzrlib/tests/lock_helpers.py", line 55, in __getattr__
    return getattr(self._other, attr)
  File "/home/mbp/bzr/remove-controlfiles/bzrlib/remote.py", line 2242, in control_files
    raise NotImplementedError("RemoteBranch.control_files is no longer supported")
NotImplementedError: RemoteBranch.control_files is no longer supported

but I think those tests sholud be locking the branch, not its control_files