calling an unknown method logs noise (do_end, and a backtrace)

 affects bzr
 status confirmed
 importance high

(this alarms users unnecessarily)

vvvv[log from
bzrlib.tests.test_remote.TestBzrDirOpenBranch.test_backwards_compat]
16.111 Traceback (most recent call last):
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 893, in accept_bytes
    _StatefulDecoder.accept_bytes(self, bytes)
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 396, in accept_bytes
    self.state_accept()
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 1027, in _state_accept_expecting_structure
    raise errors.SmartMessageHandlerError(sys.exc_info())
SmartMessageHandlerError: The message handler raised an exception:
Traceback (most recent call last):
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 1025, in _state_accept_expecting_structure
    self.message_handler.structure_part_received(structure)
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/message.py",
line 128, in structure_part_received
    self._args_received(structure)
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/message.py",
line 137, in _args_received
    self.request_handler.dispatch_command(args[0], args[1:])
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/request.py",
line 256, in dispatch_command
    raise errors.UnknownSmartMethod(cmd)
UnknownSmartMethod: The server does not recognise the
'BzrDir.open_branchV2' request.

16.112 Traceback (most recent call last):
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 893, in accept_bytes
    _StatefulDecoder.accept_bytes(self, bytes)
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 388, in accept_bytes
    self.state_accept()
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 998, in _state_accept_expecting_message_part
    self.done()
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 1036, in done
    raise errors.SmartMessageHandlerError(sys.exc_info())
SmartMessageHandlerError: The message handler raised an exception:
Traceback (most recent call last):
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/protocol.py",
line 1034, in done
    self.message_handler.end_received()
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/message.py",
line 161, in end_received
    self.request_handler.end_received()
  File
"/home/robertc/source/baz/branch.roundtrips/bzrlib/smart/request.py",
line 302, in end_received
    self._run_handler_code(self._command.do_end, (), {})
AttributeError: 'NoneType' object has no attribute 'do_end'