alexmingoia/koa-router — pull request #57 by dead-horse (2014-03-14 09:49:14+00:00)
Title: if capture is undefiend, do not decodeURIComponent

see the testcase

```
'/api'.match(/^\/api(\/.+)?/)
// =>
[ '/api', undefined, index: 0, input: '/api' ]
```

and `decodeURIComponent(undefined)` get `'undefiend'`