diff -r 000000000000 -r 6474c204b198 browser/components/sessionstore/test/browser_447951.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/sessionstore/test/browser_447951.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function test() {
+  /** Test for Bug 447951 **/
+
+  waitForExplicitFinish();
+  const baseURL = "http://mochi.test:8888/browser/" +
+    "browser/components/sessionstore/test/browser_447951_sample.html#";
+
+  // Make sure the functionality added in bug 943339 doesn't affect the results
+  gPrefService.setIntPref("browser.sessionstore.max_serialize_back", -1);
+  gPrefService.setIntPref("browser.sessionstore.max_serialize_forward", -1);
+  registerCleanupFunction(function () {
+    gPrefService.clearUserPref("browser.sessionstore.max_serialize_back");
+    gPrefService.clearUserPref("browser.sessionstore.max_serialize_forward");
+  });
+
+  let tab = gBrowser.addTab();
+  whenBrowserLoaded(tab.linkedBrowser, function() {
+    let tabState = { entries: [] };
+    let max_entries = gPrefService.getIntPref("browser.sessionhistory.max_entries");
+    for (let i = 0; i < max_entries; i++)
+      tabState.entries.push({ url: baseURL + i });
+
+    ss.setTabState(tab, JSON.stringify(tabState));
+    whenTabRestored(tab, function() {
+      SyncHandlers.get(tab.linkedBrowser).flush();
+      tabState = JSON.parse(ss.getTabState(tab));
+      is(tabState.entries.length, max_entries, "session history filled to the limit");
+      is(tabState.entries[0].url, baseURL + 0, "... but not more");
+
+      // visit yet another anchor (appending it to session history)
+      tab.linkedBrowser.contentDocument.querySelector("a").click();
+
+      function check() {
+        SyncHandlers.get(tab.linkedBrowser).flush();
+        tabState = JSON.parse(ss.getTabState(tab));
+        if (tabState.entries[tabState.entries.length - 1].url != baseURL + "end") {
+          // It may take a few passes through the event loop before we
+          // get the right URL.
+          executeSoon(check);
+          return;
+        }
+
+        is(tab.linkedBrowser.currentURI.spec, baseURL + "end",
+           "the new anchor was loaded");
+        is(tabState.entries[tabState.entries.length - 1].url, baseURL + "end",
+           "... and ignored");
+        is(tabState.entries[0].url, baseURL + 1,
+           "... and the first item was removed");
+
+        // clean up
+        gBrowser.removeTab(tab);
+        finish();
+      }
+
+      check();
+    });
+  });
+}