fix(multicast): fix a bug that caused multicast to omit messages after termination

[trxcllnt]

ConnectableObservable as the multicast selector function source argument would omit events after source termination when used with historic Subjects.

Simple repro example:

Observable.of(1, 2).multicast(
  ( ) => new ReplaySubject(1),
  (x) => x.concat(x.takeLast(1)))
  .toArray()
  .subscribe((arr) => {
    if (arr.toString() !== `1,2,2`) {
      throw 'multicast missed the `takeLast(1)` event';
    }
  });

[coveralls]

Coverage decreased (-0.06%) to 96.978% when pulling c0815c7 on trxcllnt:multicast-with-selector-unsubscribe-fix into 1bee98a on ReactiveX:master.

[staltz]

LGTM

[coveralls]

Coverage decreased (-0.06%) to 96.978% when pulling c0815c7 on trxcllnt:multicast-with-selector-unsubscribe-fix into 1bee98a on ReactiveX:master.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.