Merge pull request #463 from mvegter/mvegter-patch-correct-ext-info-l…

…ogging

Do not falsely log support for ext-info if the server did not return 'ext-info-s'

src/main/java/com/jcraft/jsch/Session.java

@@ -602,7 +602,7 @@ private KeyExchange receive_kexinit(Buffer buf) throws Exception {
 
       if (enable_server_sig_algs) {
         doExtInfo = checkServerExtInfo();
-        if (getLogger().isEnabled(Logger.INFO)) {
+        if (doExtInfo && getLogger().isEnabled(Logger.INFO)) {
           getLogger().log(Logger.INFO, "ext-info messaging supported by server");
         }
       }