Regression when calling a union of function types

[whatisaphone]

TypeScript Version: 2.0.3 (This is a regression from version 2.0.0)

Code

type DoubleFunc = ((x: number) => void) | ((x: any) => void);

function call(f: DoubleFunc) {
    f(5);
}

Expected behavior:

I would expect the call to succeed, since the argument types satisfy both halves of the union.

Actual behavior:

error TS2349: Cannot invoke an expression whose type lacks a call signature.

[RyanCavanaugh]

Duplicate #10025