authentication.conf user name setting is ignored when using OpenSSH

[Adam Glauser]

I can use the sftp transport as expected by doing something like
  bzr info sftp://name@server/path/to/branch

I add to authentication.conf
  [test]
  scheme=ssh
  host=server
  user=name

or even just
  [test]
  user=name

I expect to be able to use:
  bzr info sftp://server/path/to/branch

but I get the error
  Permission denied (publickey).
  bzr: ERROR: Unable to connect to SSH host code.brazossoftware.com; EOF during negotiation

It works if I set BZR_SSH=paramiko

Perhaps similar to https://bugs.launchpad.net/bzr/+bug/203186