fix notifications sometimes not rendering (#1905)

* fix notifications sometimes not rendering

* fix empty timeline fragment as well

* add link to github issue as explanation

app/src/main/java/com/keylesspalace/tusky/fragment/NotificationsFragment.java

@@ -75,7 +75,6 @@ import com.keylesspalace.tusky.util.ListUtils;
 import com.keylesspalace.tusky.util.NotificationTypeConverterKt;
 import com.keylesspalace.tusky.util.PairedList;
 import com.keylesspalace.tusky.util.StatusDisplayOptions;
-import com.keylesspalace.tusky.util.ThemeUtils;
 import com.keylesspalace.tusky.util.ViewDataUtils;
 import com.keylesspalace.tusky.view.BackgroundMessageView;
 import com.keylesspalace.tusky.view.EndlessOnScrollListener;
@@ -1275,7 +1274,9 @@ public class NotificationsFragment extends SFragment implements
             if (isAdded()) {
                 adapter.notifyItemRangeInserted(position, count);
                 Context context = getContext();
-                if (position == 0 && context != null) {
+                // scroll up when new items at the top are loaded while being at the start
+                // https://github.com/tuskyapp/Tusky/pull/1905#issuecomment-677819724
+                if (position == 0 && context != null && adapter.getItemCount() != count) {
                     recyclerView.scrollBy(0, Utils.dpToPx(context, -30));
                 }
             }

app/src/main/java/com/keylesspalace/tusky/fragment/TimelineFragment.java

@@ -1448,7 +1448,9 @@ public class TimelineFragment extends SFragment implements
             if (isAdded()) {
                 adapter.notifyItemRangeInserted(position, count);
                 Context context = getContext();
-                if (position == 0 && context != null) {
+                // scroll up when new items at the top are loaded while being in the first position
+                // https://github.com/tuskyapp/Tusky/pull/1905#issuecomment-677819724
+                if (position == 0 && context != null && adapter.getItemCount() != count) {
                     if (isSwipeToRefreshEnabled)
                         recyclerView.scrollBy(0, Utils.dpToPx(context, -30));
                     else