Server: fix new OpenSSH key usage

Fixes: #766

Author: mscdex

lib/server.js

@@ -47,6 +47,8 @@ function Server(cfg, listener) {
       privateKey = parseKey(hostKeys_[i].key, hostKeys_[i].passphrase);
     if (privateKey instanceof Error)
       throw new Error('Cannot parse privateKey: ' + privateKey.message);
+    if (Array.isArray(privateKey))
+      privateKey = privateKey[0]; // OpenSSH's newer format only stores 1 key for now
     if (privateKey.getPrivatePEM() === null)
       throw new Error('privateKey value contains an invalid private key');
     if (hostKeys[privateKey.type])