Paged lists stop loading new items after the screen gets rotated

[Fs00]

I've encountered a bug in all paged lists (releases list, commits list, stargazers list... actually all those inheriting from PagedDataBaseFragment) caused by screen rotation.
Basically, after the user rotates the screen, scrolling at the bottom of the paged list doesn't trigger the loading of the next page. The Loading... indicator is shown but nothing happens.

[maniac103]

Initial inspection shows this is due to RxLoader not subscribing to the upstream observable if it can deliver a previously loaded value, which is why mPageSubject.onNext(mNextPage) becomes a no-op because mPageSubject does not have any observers.
Not sure about the correct fix though...