Grunt: a dynamic banner can include src file lists!

Gruntfile.js

module.exports = function(grunt) {
  // Project configuration.
  grunt.initConfig({
    // This has to be attached as a property of either grunt, global, or set
    // in the config like so (the names here are arbitrary).
    _util: {path: require('path')},
    // Task config.
    banner_test: {
      options: {
        banner: '/* (c) <%= grunt.template.today("yyyy") %>, etc.' +
          '<% if (grunt.task.current.filesSrc.length > 1) { %>' +
          ' Includes: <%= grunt.task.current.filesSrc.map(_util.path.basename).join(", ") %>' +
          '<% } %>' +
          ' */',
      },
      nofiles: {},
      onefile: {
        files: [
          {src: 'lib/grunt.js', dest: 'build/grunt.min.js'},
        ]
      },
      manyfiles: {
        files: [
          {src: 'lib/grunt.js', dest: 'build/grunt.min.js'},
          {src: 'lib/grunt/cli.js', dest: 'build/grunt/cli.min.js'},
          {src: 'lib/grunt/config.js', dest: 'build/grunt/config.min.js'},
        ]
      },
    },
  });

  // Sample task.
  grunt.registerMultiTask('banner_test', function() {
    var options = this.options({});
    console.log('Banner:', options.banner);
  });

  grunt.registerTask('default', ['banner_test']);

};

output.txt

$ grunt
Running "banner_test:nofiles" (banner_test) task
Banner: /* (c) 2013, etc. */

Running "banner_test:onefile" (banner_test) task
Banner: /* (c) 2013, etc. */

Running "banner_test:manyfiles" (banner_test) task
Banner: /* (c) 2013, etc. Includes: grunt.js, cli.js, config.js */

Done, without errors.