fix reducing noise on connectivity testing

koji-setup/koji-add-builder.sh

@@ -50,7 +50,8 @@ if [ -z $KOJI_BUILD_FQDN ] ; then
     KOJI_BUILD_FQDN=$KOJI_HUB_FQDN
 fi
 
-if [ ! nc -z $KOJI_BUILD_FQDN 22 2>/dev/null ] ; then
+RESP=$(nc -z $KOJI_BUILD_FQDN 22 2>&1 | grep succeeded)
+if [[ -z $RESP ]] ; then
         echo "I cannot connect to $KOJI_BUILD_FQDN! Is it online? "
         echo "Options:"
         echo "- turn on the server"