diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8/extensions/regress-475971.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8/extensions/regress-475971.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,58 @@
+// |reftest| skip
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 475971;
+var summary = 'js_CheckRedeclaration should unlock object on failures';
+var actual = '';
+var expect = '';
+
+
+//-----------------------------------------------------------------------------
+test();
+//-----------------------------------------------------------------------------
+
+function test()
+{
+  enterFunc ('test');
+  printBugNumber(BUGNUMBER);
+  printStatus (summary);
+
+  if (typeof scatter != 'function')
+  {
+    print(expect = actual = 
+          'Test skipped - requires threaded build with scatter');
+  }
+  else
+  {
+    function x() { return 1; };
+
+    // g must run sufficiently long to ensure that the global scope is accessed
+    // from the parallel threads.
+    function g()
+    {
+      var sum = 0;
+      try {
+        for (var i = 0; i != 10000; ++i) {
+          sum += x();
+        }
+      } catch (e) { }
+    }
+
+    scatter([g, g]);
+
+    try {
+      eval("const x = 1");
+    } catch (e) { }
+
+    scatter([g, g]);
+
+    print("Done");
+  }
+  reportCompare(expect, actual, summary);
+
+  exitFunc ('test');
+}