Fix IsEmpty to return the right thing

src/github.com/matrix-org/dendrite/syncapi/types/types.go

@@ -77,11 +77,11 @@ func NewResponse(pos StreamPosition) *Response {
 // IsEmpty returns true if the response is empty, i.e. used to decided whether
 // to return the response immediately to the client or to wait for more data.
 func (r *Response) IsEmpty() bool {
-	return len(r.Rooms.Join) > 0 ||
-		len(r.Rooms.Invite) > 0 ||
-		len(r.Rooms.Leave) > 0 ||
-		len(r.AccountData.Events) > 0 ||
-		len(r.Presence.Events) > 0
+	return len(r.Rooms.Join) == 0 &&
+		len(r.Rooms.Invite) == 0 &&
+		len(r.Rooms.Leave) == 0 &&
+		len(r.AccountData.Events) == 0 &&
+		len(r.Presence.Events) == 0
 }
 
 // JoinResponse represents a /sync response for a room which is under the 'join' key.