From 833e3f645ea823bc80ecdf7729cf59f036114bea Mon Sep 17 00:00:00 2001
From: Till Faelligen <2353100+S7evinK@users.noreply.github.com>
Date: Fri, 19 Aug 2022 15:13:25 +0200
Subject: [PATCH] Also ignore join -> join changes in key changes

---
 syncapi/internal/keychange.go | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/syncapi/internal/keychange.go b/syncapi/internal/keychange.go
index 23824e366..c5180e338 100644
--- a/syncapi/internal/keychange.go
+++ b/syncapi/internal/keychange.go
@@ -18,14 +18,16 @@ import (
 	"context"
 	"strings"
 
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+	"github.com/sirupsen/logrus"
+	"github.com/tidwall/gjson"
+
 	keyapi "github.com/matrix-org/dendrite/keyserver/api"
 	keytypes "github.com/matrix-org/dendrite/keyserver/types"
 	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/syncapi/storage"
 	"github.com/matrix-org/dendrite/syncapi/types"
-	"github.com/matrix-org/gomatrixserverlib"
-	"github.com/matrix-org/util"
-	"github.com/sirupsen/logrus"
 )
 
 // DeviceOTKCounts adds one-time key counts to the /sync response
@@ -277,6 +279,10 @@ func membershipEventPresent(events []gomatrixserverlib.ClientEvent, userID strin
 		// it's enough to know that we have our member event here, don't need to check membership content
 		// as it's implied by being in the respective section of the sync response.
 		if ev.Type == gomatrixserverlib.MRoomMember && ev.StateKey != nil && *ev.StateKey == userID {
+			// ignore e.g. join -> join changes
+			if gjson.GetBytes(ev.Unsigned, "prev_content.membership").Str == gjson.GetBytes(ev.Content, "membership").Str {
+				continue
+			}
 			return true
 		}
 	}