Incorrect type signatures for concatAll and mergeAll operators

RxJS version: 5.4.2

Code to reproduce:

const fromEvent = Rx.Observable.fromEvent;
const mouseEvents = Rx.Observable.of([fromEvent(document, "click"), fromEvent(document, "mouseenter"), fromEvent(document, "mouseleave")]); 

mouseEvents.concatAll().mapTo(null);
mouseEvents.mergeAll().mapTo(null);

Expected behavior: Code compiles without error.

Actual behavior: Type error: "[ts] Property ‘mapTo’ does not exist on type ‘Observable<{}>[]’.

Additional information: Incorrect type signatures are-

function concatAll<T>(this: Observable<T>): T;
function concatAll<T, R>(this: Observable<T>): Subscribable<R>;

function mergeAll<T>(this: Observable<T>, concurrent?: number): T;
function mergeAll<T, R>(this: Observable<T>, concurrent?: number): Subscribable<R>;

They should be (I believe):

function concatAll<T extends ObservableInput<R>, R>(this: Observable<T>): Observable<R>;

function mergeAll<T extends ObservableInput<R>, R>(this: Observable<T>, concurrent?: number): Observable<R>;

[benlesh]

Closed by #3321

[tvald]

Can we please fix this without waiting for a major release? This is an active issue, with two separate PRs to (partially) fix it on master in the last month: #2779, #2760

The existing typings for mergeAll() are wrong and unusable. It should be trivial to drop in the correct typing from #2779: https://github.com/ReactiveX/rxjs/pull/2690/files#diff-287d1762ff7b138d92ddcb79627353f7