Grunt file_strip_banner directive bug

first.js

// Test comment.
// This should get stripped out!
// But it doesn't.
(function() {
	var test = 'foo';
})();

grunt.js

/*global module:false*/
module.exports = function(grunt) {
  grunt.initConfig({
    concat: {
      dist: {
        src: ['<file_strip_banner:first.js:line>',
              '<file_strip_banner:second.js:line>'],
        dest: 'fail.js'
      }
    }
  });
  grunt.registerTask('default', 'concat');
};

second.js

// You're still going to see these comments in fail.js.
// <file_strip_banner:whatever.js:line> doesn't strip them out.
// :(
(function() {
	var test = 'bar';
})();