git remotes that have git-annex and git "installed" using the linux
standalone tarball (or the OSX dmg) may not have git-receive-pack in PATH.

To make `git annex sync` and `git push` etc work on such a remote,
it needs to have a dedicated ssh key that runs git-annex-shell and uses it
to run the command.

The assistant sets that up when it sets up a dedicated ssh key. However, if
the server can be sshed into without a password using an existing ssh key,
the assistant re-uses that key.

The assistant should either always set up a dedicated ssh key, even when
not otherwise needed, or it should probe to see if git-receive-pack and
git-send-pack can be run as part of its probing, and set up a dedicated
ssh key when they cannot be. --[[Joey]] 

> After recent sshpassword changes, the webapp sets up a dedicated ssh key
> by default. If the user chooses to use an existing ssh key, it will be
> used. So this is less likely to be a problem. --[[Joey]] 

[[!tag confirmed]]