From c82a72b179d680722d64f16bf03aeb10d1d60f20 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Fri, 15 Jan 2021 14:32:27 +0000
Subject: [PATCH] Only do this for non-state events, since state events will
 always result in state change at extremities

---
 .../internal/input/input_latest_events.go     | 46 ++++++++++---------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/roomserver/internal/input/input_latest_events.go b/roomserver/internal/input/input_latest_events.go
index 9517350e9..c9264a27d 100644
--- a/roomserver/internal/input/input_latest_events.go
+++ b/roomserver/internal/input/input_latest_events.go
@@ -204,30 +204,32 @@ func (u *latestEventsUpdater) latestState() error {
 	// Work out if the state at the extremities has actually changed
 	// or not. If they haven't then we won't bother doing all of the
 	// hard work.
-	stateChanged := false
-	oldStateNIDs := make([]types.StateSnapshotNID, 0, len(u.oldLatest))
-	newStateNIDs := make([]types.StateSnapshotNID, 0, len(u.latest))
-	for _, old := range u.oldLatest {
-		oldStateNIDs = append(oldStateNIDs, old.BeforeStateSnapshotNID)
-	}
-	for _, new := range u.latest {
-		newStateNIDs = append(newStateNIDs, new.BeforeStateSnapshotNID)
-	}
-	oldStateNIDs = state.UniqueStateSnapshotNIDs(oldStateNIDs)
-	newStateNIDs = state.UniqueStateSnapshotNIDs(newStateNIDs)
-	if len(oldStateNIDs) != len(newStateNIDs) {
-		stateChanged = true
-	} else {
-		for i := range oldStateNIDs {
-			if oldStateNIDs[i] != newStateNIDs[i] {
-				stateChanged = true
-				break
+	if u.event.StateKey() == nil {
+		stateChanged := false
+		oldStateNIDs := make([]types.StateSnapshotNID, 0, len(u.oldLatest))
+		newStateNIDs := make([]types.StateSnapshotNID, 0, len(u.latest))
+		for _, old := range u.oldLatest {
+			oldStateNIDs = append(oldStateNIDs, old.BeforeStateSnapshotNID)
+		}
+		for _, new := range u.latest {
+			newStateNIDs = append(newStateNIDs, new.BeforeStateSnapshotNID)
+		}
+		oldStateNIDs = state.UniqueStateSnapshotNIDs(oldStateNIDs)
+		newStateNIDs = state.UniqueStateSnapshotNIDs(newStateNIDs)
+		if len(oldStateNIDs) != len(newStateNIDs) {
+			stateChanged = true
+		} else {
+			for i := range oldStateNIDs {
+				if oldStateNIDs[i] != newStateNIDs[i] {
+					stateChanged = true
+					break
+				}
 			}
 		}
-	}
-	if !stateChanged {
-		u.newStateNID = u.oldStateNID
-		return nil
+		if !stateChanged {
+			u.newStateNID = u.oldStateNID
+			return nil
+		}
 	}
 
 	// Get a list of the current latest events. This may or may not