Previously, this would assert:
```ts
exports.undeclared.n = 1;
```
Because undeclared was never declared in any recognised way. Now it no
longer asserts, but does not bind. That's because the full pattern
starts with the line `exports = require('./x')` and assumes that x.js
declares `undeclared`. I am not sure how to bind this. The new test
contains this pattern in case I figure it out.
