diff -r 000000000000 -r 6474c204b198 browser/devtools/webconsole/test/browser_webconsole_console_trace_duplicates.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/webconsole/test/browser_webconsole_console_trace_duplicates.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+/* 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() {
+  const TEST_URI = "http://example.com/browser/browser/devtools/webconsole/test/test-bug_939783_console_trace_duplicates.html";
+
+  Task.spawn(runner).then(finishTest);
+
+  function* runner() {
+    const {tab} = yield loadTab("data:text/html;charset=utf8,<p>hello");
+    const hud = yield openConsole(tab);
+
+    content.location = TEST_URI;
+
+    yield waitForMessages({
+      webconsole: hud,
+      messages: [{
+        name: "console.trace output for foo1()",
+        text: "foo1()",
+        repeats: 2,
+        consoleTrace: {
+          file: "test-bug_939783_console_trace_duplicates.html",
+          fn: "foo3()",
+        },
+      }, {
+        name: "console.trace output for foo1b()",
+        text: "foo1b()",
+        consoleTrace: {
+          file: "test-bug_939783_console_trace_duplicates.html",
+          fn: "foo3()",
+        },
+      }],
+    });
+  }
+}