title: Watchify update event never fires in Virtualbox
body: <p>I am trying to get watchify working with Gulp but it seems that the 'update' event is never fired.</p>
  
  <p>Here's my gulpfile.js:</p>
  
  <pre><code>"use strict";
  
  var gulp = require('gulp');
  var browserify = require('browserify');
  var source = require("vinyl-source-stream");
  var watchify = require('watchify');
  
  var bundler = watchify(browserify({entries: ['./client/app/app.js'], cache: {}, packageCache: {}, fullPaths: true}));
  
  gulp.task('js', bundle); 
  
  function bundle() {
      console.log('bundle');
      return bundler.bundle()
      .pipe(source('bundle.js'))
      .pipe(gulp.dest('./dist'));
  }
  
  // this is never fired!
  bundler.on('update', bundle);
  </code></pre>
  
  <p>However, when I explicitly watch the files without watchify it works:</p>
  
  <pre><code>"use strict";
  
  var gulp = require('gulp');
  var browserify = require('browserify');
  var source = require("vinyl-source-stream");
  var watchify = require('watchify');
  
  function bundle() {
      console.log('bundle');
      return browserify('./client/app/app.js')
      .bundle()
      .pipe(source('bundle.js'))
      .pipe(gulp.dest('./dist/'));
  }
  
  gulp.task('browserify', bundle);
  
  gulp.task('js', function() {
      bundle();
      gulp.watch(['client/**/*.js'], ['browserify']);
  });
  </code></pre>
  
  <p>I've tried numerous examples but with watchify the bundle never updates.</p>
  
  <p>I'm running Gulp inside a Vagrant VM, host is OSX Yosemite, guest is Ubuntu 14.04.</p>
  
  <p>Any help is greatly appreciated!</p>