title: gulp-include with gulp-uglify doesn't work
body: <p>I have a <code>gulp.task 'scripts'</code> that uses <code>gulp-uglify</code>. Then I also added <code>gulp-import</code> and it didn't work. If i do only <code>uglify</code> it works. If I do only <code>import</code> it works. But if i do both at the same time it doesn't work.
  Here is the function:</p>
  
  <pre><code>gulp.task('scripts', function(){
      gulp.src([
              'testgulp/**/*.js', '!testgulp/**/_*.js', '!testgulp/**/*.min.js'
          ])
          .pipe(include()) //if I comment only this line, uglify works
              .on('error', console.log)
          .pipe(uglify()) //if I comment only this line, include works
          .pipe(rename({ suffix: '.min' }))
          .pipe(gulp.dest(function(file) { return file.base; }));
  
  });
  </code></pre>
  
  <p>And then on terminal I have this response when try to do both:</p>
  
  <pre><code>/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/map-stream/index.js:103
          throw err
          ^
  GulpUglifyError: unable to minify JavaScript
      at createError (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/gulp-uglify/lib/create-error.js:6:14)
      at wrapper (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/gulp-uglify/node_modules/lodash/_createHybrid.js:87:15)
      at trycatch (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/gulp-uglify/minifier.js:26:12)
      at DestroyableTransform.minify [as _transform] (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/gulp-uglify/minifier.js:76:19)
      at DestroyableTransform.Transform._read (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/through2/node_modules/readable-stream/lib/_stream_transform.js:159:10)
      at DestroyableTransform.Transform._write (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/through2/node_modules/readable-stream/lib/_stream_transform.js:147:83)
      at doWrite (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:313:64)
      at writeOrBuffer (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:302:5)
      at DestroyableTransform.Writable.write (/Applications/MAMP/htdocs/git/personal-sandrina-p/_main/v3/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:241:11)
      at Stream.ondata (stream.js:31:26)
  </code></pre>
  
  <p>I'm moving away from Koala App and the append/prepend feature was awesome, so i would like to do the same with Gulp. I tried gulp-include and gulp-import, both has the same problem. What i'm doing wrong? 
  Thank you :)</p>
  
  <p><strong>-EDIT-</strong>
  i also tried gulp-sync and hardcode a timeout() on minifyit task, but doesn't fix the problem...</p>