handle deprecated files redirect on /notebooks

IPython/html/notebook/handlers.py

@@ -26,7 +26,7 b' class NotebookHandler(IPythonHandler):'
         try:
             model = cm.get(path, content=False)
         except web.HTTPError as e:
-            if e.code == 404 and 'files' in path.split('/'):
+            if e.status_code == 404 and 'files' in path.split('/'):
                 # 404, but '/files/' in URL, let FilesRedirect take care of it
                 return FilesRedirectHandler.get(self, path)
             else: