Check SSH keys at time of running launchpad login and provide informative error messages if something is wrong

When attempting to grab a branch on a new machine, I first used the launchpad-login command to specify my username, which appeared to work fine. Next, I tried to fetch a branch, but was greeted with the following error message:

$ bzr branch lp:myproject
Permission denied (publickey).
bzr: ERROR: Connection closed: please check connectivity and permissions (and try -Dhpss if further diagnosis is required)

It says publickey sort of in passing, but what I paid most attention to was the suggestions in the error message: "check connectivity and permissions..."

So in order to try and get more details I tried running the command with the suggested arguments:

$ bzr branch lp:myproj -Dhpss
Permission denied (publickey).
bzr: ERROR: exceptions.AttributeError: 'ProtocolThreeDecoder' object has no attribute '_in_buffer'

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 857, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 797, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 499, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 840, in run
    from_location)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 878, in open_tree_or_branch
    bzrdir = klass.open(location)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 756, in open
    return BzrDir.open_from_transport(t, _unsupported=_unsupported)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 798, in open_from_transport
    return format.open(transport, _found=True)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 1725, in open
    return self._open(transport)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 2605, in _open
    return remote.RemoteBzrDir(transport)
  File "/usr/lib/python2.5/site-packages/bzrlib/remote.py", line 76, in __init__
    response = self._client.call('BzrDir.open', path)
  File "/usr/lib/python2.5/site-packages/bzrlib/smart/client.py", line 111, in call
    result, protocol = self.call_expecting_body(method, *args)
  File "/usr/lib/python2.5/site-packages/bzrlib/smart/client.py", line 124, in call_expecting_body
    method, args, expect_response_body=True)
  File "/usr/lib/python2.5/site-packages/bzrlib/smart/client.py", line 72, in _call_and_read_response
    expect_body=expect_response_body)
  File "/usr/lib/python2.5/site-packages/bzrlib/smart/message.py", line 258, in read_response_tuple
    self._wait_for_response_args()
  File "/usr/lib/python2.5/site-packages/bzrlib/smart/message.py", line 224, in _wait_for_response_args
    self._read_more()
  File "/usr/lib/python2.5/site-packages/bzrlib/smart/message.py", line 243, in _read_more
    self._protocol_decoder._in_buffer[:10],
AttributeError: 'ProtocolThreeDecoder' object has no attribute '_in_buffer'

bzr 1.6.1 on python 2.5.2 (linux2)
arguments: ['/usr/bin/bzr', 'branch', 'lp:myproj', '-Dhpss']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_US.UTF-8'
plugins:
  avahi /usr/lib/python2.5/site-packages/bzrlib/plugins/avahi [0.3.0dev0]
  bzrtools /usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools [1.6.0]
  dbus /usr/lib/python2.5/site-packages/bzrlib/plugins/dbus [unknown]
  gtk /usr/lib/python2.5/site-packages/bzrlib/plugins/gtk [0.95.0]
  launchpad /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [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.

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Again, not very helpful (to me).

After searching around the web some I found someone with a similar error message (https://answers.edge.launchpad.net/launchpad/+question/56842) and they were told to check their SSH keys. Sure enough, I had forgotten to add my public key for the new machine. Add the public key fixed the problem right away.

So my request is:

Would it be possible to

1) Check the ssh key at the time the user uses the command "launchpad-login" and display a simple message "e.g. You have not yet added a public ssh key for this machine. etc," and

 2) Provide a more informative message when the user tries to do some other action?

Both of these would be very helpful :)