From a00e318d735b0772f208bc061517686f81a2ab2b Mon Sep 17 00:00:00 2001
From: Kegan Dougal <kegan@matrix.org>
Date: Mon, 14 Dec 2015 12:28:04 +0000
Subject: [PATCH] Fix pagination - set prev_batch at the right time

---
 lib/sync.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/sync.js b/lib/sync.js
index cd4c6e22a..9335cdd8f 100644
--- a/lib/sync.js
+++ b/lib/sync.js
@@ -301,9 +301,16 @@ SyncApi.prototype._sync = function(syncOptions, attempt) {
                     // nuke the timeline so we don't get holes
                     room.timeline = [];
                 }
+
+                // we want to set a new pagination token if this is the first time
+                // we've made this room or if we're nuking the timeline
+                var paginationToken = null;
+                if (joinObj.isBrandNewRoom || joinObj.timeline.limited) {
+                    paginationToken = joinObj.timeline.prev_batch;
+                }
+
                 self._processRoomEvents(
-                    room, stateEvents, timelineEvents,
-                    joinObj.timeline ? joinObj.timeline.prev_batch : null
+                    room, stateEvents, timelineEvents, paginationToken
                 );
                 room.addEvents(ephemeralEvents);
                 room.addEvents(accountDataEvents);