Prevent multiple registrations to eventHub on same TimelineFragment (#879)

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

@@ -119,6 +119,7 @@ public class TimelineFragment extends SFragment implements
     public TimelineCases timelineCases;
     @Inject
     public EventHub eventHub;
+    private boolean eventRegistered = false;
 
     private SwipeRefreshLayout swipeRefreshLayout;
     private RecyclerView recyclerView;
@@ -304,7 +305,7 @@ public class TimelineFragment extends SFragment implements
                 break;
             }
         }
-        if(statuses.size() == 0) {
+        if (statuses.size() == 0) {
             nothingMessageView.setVisibility(View.VISIBLE);
         }
     }
@@ -378,6 +379,7 @@ public class TimelineFragment extends SFragment implements
         }
         recyclerView.addOnScrollListener(scrollListener);
 
+        if (!eventRegistered) {
             eventHub.getEvents()
                     .observeOn(AndroidSchedulers.mainThread())
                     .as(autoDisposable(from(this, Lifecycle.Event.ON_DESTROY)))
@@ -413,6 +415,8 @@ public class TimelineFragment extends SFragment implements
                             handleStatusComposeEvent(status);
                         }
                     });
+            eventRegistered = true;
+        }
     }
 
     @Override
@@ -583,7 +587,7 @@ public class TimelineFragment extends SFragment implements
                     "Expected StatusViewData.Concrete, got %s instead at position: %d of %d",
                     status == null ? "<null>" : status.getClass().getSimpleName(),
                     position,
-                    statuses.size() -1
+                    statuses.size() - 1
             ));
             return;
         }