title: execFileSync running asyncronously
body: <p>we have a weird issue where for some developers the node.js execFileSync  function is running asynchronously and <strong>NOT</strong> synchronously the way that it is supposed to. We think this is being caused by some environmental difference between the machines that have the issue and those that do not but we have not been able to find the cause.
  Has anyone ever experienced this before?</p>
  
  <p>Here is a simple example. We have multiple calls to this block of code because we need to call some external scripts to perform some clean up in between runs but on the machines with the issue the code does not wait for the script to finish and return before continuing so the script could end up running multiple times at once instead of consecutively.</p>
  
  <pre><code>execFileSync(batchPath, {stdio:[0,1,2]}, function(error, stderr, stdout) {
         console.log(stderr);
         console.log(stdout);
         if (error !== null) {
             console.log('exec error: ', error);
         }
      });
  </code></pre>
  
  <p>Thanks for any ideas on what could cause this.</p>