SSH to localhost can fail in tests if the host key has changed #348

SAGA does some ssh-ing to localhost when testing. However, it uses strict host key checking, which can cause it to fail (or maybe hang waiting for a user prompt; I don't recall exactly) when there is no localhost in known_hosts.

For that reason, the test suite does a "preloading" ssh to localhost with strict host checking disabled, which puts the right key in known_hosts. However, this can fail, too, if there is a host key there already and localhost changes its key. It may be possible to fix this using something like "NoHostAuthenticationForLocalhost", but some work is needed to figure it out.