Fix home timeline perpetually reloading when empty (#10130)

Regression from #6876

app/javascript/mastodon/features/home_timeline/index.js

@@ -16,7 +16,7 @@ const messages = defineMessages({
 
 const mapStateToProps = state => ({
   hasUnread: state.getIn(['timelines', 'home', 'unread']) > 0,
-  isPartial: state.getIn(['timelines', 'home', 'items', 0], null) === null,
+  isPartial: state.getIn(['timelines', 'home', 'isPartial']),
 });
 
 export default @connect(mapStateToProps)

app/javascript/mastodon/reducers/timelines.js

@@ -29,6 +29,8 @@ const initialTimeline = ImmutableMap({
 const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, isLoadingRecent) => {
   return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
     mMap.set('isLoading', false);
+    mMap.set('isPartial', isPartial);
+
     if (!next && !isLoadingRecent) mMap.set('hasMore', false);
 
     if (!statuses.isEmpty()) {