twisted.conch.client.agent.SSHAgentClient.getPublicKey returns a str, triggers deprecated behavior from twisted.conch.client.default.SSHUserAuthClient.getPublicKey

New submission from exarkun <[email protected]>:

`twisted.conch.client.default.SSHUserAuthClient.getPublicKey` is supposed to return a `twisted.conch.ssh.keys.Key` instance now.  It calls `twisted.conch.client.agent.SSHAgentClient.getPublicKey` if the environment is configured with an agent, though, which returns a `str` instance.  This results in a deprecation warning.

Either `SSHUserAuthClient` should take responsibility for converting the `str` into a `Key` before returning, or the `SSHAgentClient` should be updated to deal with `Key` objects too.

`SSHUserAuthClient` also triggers deprecation warnings in another case: if there's no agent, it uses `twisted.conch.ssh.keys.getPublicKeyString` which is deprecated and ''also'' returns a `str`, causing the same deprecation as happens in the with-agent case.


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Type     : defect
Component: conch
Keywords : 
Priority : high
Nosy     : 
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http://twistedmatrix.com/trac/ticket/3813