$ npm i babel-plugin-transform-es2015-modules-commonjs --save
npm WARN optional Skipping failed optional dependency /chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: fsevents@1.0.12
aubrey@alita:~/tmp/koa2-test$ DEBUG=koa2-test:* npm run koa

> koa2-test@0.1.0 koa /home/aubrey/tmp/koa2-test
> runkoa bin/www

bin/www
3babel presets path = /home/aubrey/tmp/koa2-test/node_modules/runkoa/node_modules/
/home/aubrey/tmp/koa2-test/node_modules/babel-core/lib/transformation/file/options/option-manager.js:204
          throw new ReferenceError(messages.get("pluginUnknown", plugin, loc, i, dirname));
          ^

ReferenceError: Unknown plugin "/home/aubrey/tmp/koa2-test/node_modules/runkoa/node_modules/babel-plugin-transform-es2015-modules-commonjs" specified in "base" at 1, attempted to resolve relative to "/home/aubrey/tmp/koa2-test/bin"
    at /home/aubrey/tmp/koa2-test/node_modules/babel-core/lib/transformation/file/options/option-manager.js:204:17
    at Array.map (native)
    at Function.normalisePlugins (/home/aubrey/tmp/koa2-test/node_modules/babel-core/lib/transformation/file/options/option-manager.js:180:20)
    at OptionManager.mergeOptions (/home/aubrey/tmp/koa2-test/node_modules/babel-core/lib/transformation/file/options/option-manager.js:300:36)
    at OptionManager.init (/home/aubrey/tmp/koa2-test/node_modules/babel-core/lib/transformation/file/options/option-manager.js:488:10)
    at compile (/home/aubrey/tmp/koa2-test/node_modules/babel-register/lib/node.js:112:69)
    at loader (/home/aubrey/tmp/koa2-test/node_modules/babel-register/lib/node.js:158:14)
    at Object.require.extensions.(anonymous function) [as .js] (/home/aubrey/tmp/koa2-test/node_modules/babel-register/lib/node.js:168:7)
    at Module.load (module.js:357:32)
    at Function.Module._load (module.js:314:12)

npm ERR! Linux 4.2.0-36-generic
npm ERR! argv "/usr/bin/nodejs" "/usr/bin/npm" "run" "koa"
npm ERR! node v5.12.0
npm ERR! npm  v3.8.6
npm ERR! code ELIFECYCLE
npm ERR! koa2-test@0.1.0 koa: `runkoa bin/www`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the koa2-test@0.1.0 koa script 'runkoa bin/www'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the koa2-test package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     runkoa bin/www
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs koa2-test
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls koa2-test
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /home/aubrey/tmp/koa2-test/npm-debug.log