this.directory('node_modules', 'project/node_modules');

yo studio
grunt

/Users/djfrsn/Code/Michelangelo/Projects/hmmm/project/node_modules/grunt/lib/grunt/template.js:36
var b = '([\s\S]+?)' + delimiters.closer.replace(/(.)/g, '\$1');
                                         ^
TypeError: Cannot call method 'replace' of undefined
at Object.template.addDelimiters (/Users/djfrsn/Code/Michelangelo/Projects/hmmm/project/node_modules/grunt/lib/grunt/template.js:36:46)
at Object.<anonymous> (/Users/djfrsn/Code/Michelangelo/Projects/hmmm/project/node_modules/grunt/lib/grunt/template.js:47:10)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.require (module.js:364:17)
at require (module.js:380:17)
at gRequire (/Users/djfrsn/Code/Michelangelo/Projects/hmmm/project/node_modules/grunt/lib/grunt.js:23:24)
at Object.<anonymous> (/Users/djfrsn/Code/Michelangelo/Projects/hmmm/project/node_modules/grunt/lib/grunt.js:30:1)