From ebd8b85072dbb795f21a31b745a024cf356ba2c9 Mon Sep 17 00:00:00 2001
From: John McLear <john@mclear.co.uk>
Date: Wed, 27 Feb 2013 16:17:50 +0000
Subject: [PATCH] patch documented here
 https://github.com/ether/etherpad-lite/issues/472 adds some stability but not
 a perfect solution

---
 src/node/handler/PadMessageHandler.js | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/node/handler/PadMessageHandler.js b/src/node/handler/PadMessageHandler.js
index 08ddde0e9..15a9b8eab 100644
--- a/src/node/handler/PadMessageHandler.js
+++ b/src/node/handler/PadMessageHandler.js
@@ -586,7 +586,14 @@ function handleUserChanges(client, message)
             // client) are relative to revision r - 1. The follow function
             // rebases "changeset" so that it is relative to revision r
             // and can be applied after "c".
-            changeset = Changeset.follow(c, changeset, false, apool);
+            try
+            {
+              changeset = Changeset.follow(c, changeset, false, apool);
+            }catch(e){
+              console.warn("Can't apply USER_CHANGES "+changeset+", possibly because of mismatched follow error");
+              client.json.send({disconnect:"badChangeset"});
+              return;
+            }
 
             if ((r - baseRev) % 200 == 0) { // don't let the stack get too deep
               async.nextTick(callback);