Incorrect `Object is possibly 'null'.` error inside `Promise.prototype.then`

[kimamula]

TypeScript Version: 2.1.4 (2.2.0-dev.20161218 also)

Code

With --strictNullChecks,

interface Foo {
 prop: string;
}

function nullableFooPromise(): Promise<Foo | null> {
 return Promise.resolve(null);
}

nullableFooPromise()
 .then(nullableFoo => nullableFoo ? nullableFoo : { prop: 'foo' })
 .then(foo => console.log(foo.prop)); // this line raises an error

Expected behavior:
I expect this to compile (it does actually when I use typescript@2.0.8).

Actual behavior:
I get an error,
index.ts(11,28): error TS2531: Object is possibly 'null'.

[aluanhaddad]

This looks to be related to #13008. The overloads for .then are not declared in the right order.