OpenSSH support in bzr

I updated my bzr openssh plugin to be a proper patch against, and got it merged. So if you have in your ~/.bazaar/plugins directory, you should remove it when upgrading.

Unfortunately there was a small problem resolving a conflict when merging it, which causes the path to get mangled a little inside _sftp_connect(). Once this is resolved, the mainline bzr should fully follow settings in ~/.ssh/config, because it will be running the same ssh binary as you normally use.

One thing I learnt when adding the support code was a quirk in the SFTP URI spec‘s interpretation of paths, which differs to gnome-vfs’s interpretation. The uri sftp://remotehost/directory is interpreted as /directory on remotehost by gnome-vfs, while the spec says that it should be interpreted as ~/directory.

To refer to /directory on remotehost, the spec says you should use sftp://remotehost/%2Fdirectory. I filed this as bug 322394.