bzr switch --force failing with ConnectionError

[Robert Collins]

 affects bzr
 status triaged
 importance medium
 done

Root cause:
 - ConnectionError is raised when probing for a branch.
 - switch catches NotBranchError, but not ConnectionError

possible fixes:
 - catch ConnectionError in Remote* and raise NotBranchError
 - catch ConnectionError in cmd_switch.

I need to think more about it, but I'm inclined to say that the
RemoteBranch logic should be catching ConnectionError.

-Rob

$ bzr -Derror switch --no-plugins --force
bzr://mbp:9990/.bzr-repo/trunk/
bzr: ERROR: bzrlib.errors.ConnectionError: Connection error: failed to connect to mbp:4155: Connection refused

Traceback (most recent call last):
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 729, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 924, in run_bzr
    ret = run(*run_argv)
  File "/Library/Python/2.6/site-packages/bzrlib/commands.py", line 560, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/Library/Python/2.6/site-packages/bzrlib/builtins.py", line 5175, in run
    branch = control_dir.open_branch()
  File "/Library/Python/2.6/site-packages/bzrlib/bzrdir.py", line 1713, in open_branch
    return format.open(self, _found=True, ignore_fallbacks=ignore_fallbacks)
  File "/Library/Python/2.6/site-packages/bzrlib/branch.py", line 1950, in open
    location, possible_transports=possible_transports)
  File "/Library/Python/2.6/site-packages/bzrlib/bzrdir.py", line 837, in open
    return BzrDir.open_from_transport(t, _unsupported=_unsupported)
  File "/Library/Python/2.6/site-packages/bzrlib/bzrdir.py", line 872, in open_from_transport
    return format.open(transport, _found=True)
  File "/Library/Python/2.6/site-packages/bzrlib/bzrdir.py", line 2053, in open
    return self._open(transport)
  File "/Library/Python/2.6/site-packages/bzrlib/bzrdir.py", line 3280, in _open
    return remote.RemoteBzrDir(transport, self)
  File "/Library/Python/2.6/site-packages/bzrlib/remote.py", line 112, in __init__
    response = self._call('BzrDir.open', path)
  File "/Library/Python/2.6/site-packages/bzrlib/remote.py", line 56, in _call
    return self._client.call(method, *args)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/client.py", line 129, in call
    result, protocol = self.call_expecting_body(method, *args)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/client.py", line 142, in call_expecting_body
    method, args, expect_response_body=True)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/client.py", line 87, in _call_and_read_response
    readv_body=readv_body, body_stream=body_stream)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/client.py", line 60, in _send_request
    encoder.call(method, *args)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/protocol.py", line 1235, in call
    self._write_end()
  File "/Library/Python/2.6/site-packages/bzrlib/smart/protocol.py", line 1106, in _write_end
    self.flush()
  File "/Library/Python/2.6/site-packages/bzrlib/smart/protocol.py", line 1073, in flush
    self._real_write_func(''.join(self._buf))
  File "/Library/Python/2.6/site-packages/bzrlib/smart/medium.py", line 390, in accept_bytes
    self._accept_bytes(bytes)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/medium.py", line 908, in _accept_bytes
    self._medium._accept_bytes(bytes)
  File "/Library/Python/2.6/site-packages/bzrlib/smart/medium.py", line 823, in _accept_bytes
    self._ensure_connection()
  File "/Library/Python/2.6/site-packages/bzrlib/smart/medium.py", line 870, in _ensure_connection
    (self._host, port, err_msg))
ConnectionError: Connection error: failed to connect to mbp:4155: Connection refused

--