concatMap() invokes inner.cancel() after inner has signaled onComplete() #6259

Reproduced with RxJava version: 2.1.9 and 2.2.3.

Flowable.just(Boolean.TRUE)
        .repeat()
        .concatMap(token -> Flowable.just("foo").doOnCancel(() -> System.out.println("Cancelled")))
        .subscribe();

Expected behavior: "Cancelled" should not appear on the console
Current behavior: "Cancelled" is printed as a result of cancel invocation.

Note that flatMap(token -> ..., 1) don't have this issue but it is significantly slower than concatMap()