Concurrently refresh trackers

app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupRestoreService.kt

@@ -394,7 +394,7 @@ class BackupRestoreService : Service() {
      */
     private fun trackingFetchObservable(manga: Manga, tracks: List<Track>): Observable<Track> {
         return Observable.from(tracks)
-            .concatMap { track ->
+            .flatMap { track ->
                 val service = trackManager.getService(track.sync_id)
                 if (service != null && service.isLogged) {
                     service.refresh(track)

app/src/main/java/eu/kanade/tachiyomi/ui/manga/track/TrackPresenter.kt

@@ -58,7 +58,7 @@ class TrackPresenter(
         refreshSubscription?.let { remove(it) }
         refreshSubscription = Observable.from(trackList)
             .filter { it.track != null }
-            .concatMap { item ->
+            .flatMap { item ->
                 item.service.refresh(item.track!!)
                     .flatMap { db.insertTrack(it).asRxObservable() }
                     .map { item }