Forgot to add the needed js file...

IPython/html/templates/notebook.html

@@ -273,6 +273,7 b' class="notebook_app"'
 <script src="{{ static_url("components/codemirror/addon/mode/multiplex.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("components/codemirror/addon/mode/overlay.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("components/codemirror/addon/edit/matchbrackets.js") }}" charset="utf-8"></script>
+<script src="{{ static_url("components/codemirror/addon/edit/closebrackets.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("components/codemirror/addon/comment/comment.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("components/codemirror/mode/htmlmixed/htmlmixed.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("components/codemirror/mode/xml/xml.js") }}" charset="utf-8"></script>