do not load pty.js when testing connection since that can crash node process

node_modules/vfs-local/localfs.js

@@ -66,6 +66,7 @@ function logToFile(message){
 module.exports = function setup(fsOptions) {
     var pty;
     if (!fsOptions.nopty) {
+        // on darwin trying to load binary for a wrong version crashes the process
         [process.env.HOME + "/.c9/node_modules/pty.js", "pty.js", "pty.nw.js"].some(function(p) {
             try {
                 pty = require(p);