From a45e99717616967bf6e44cf9be983ab31b77a501 Mon Sep 17 00:00:00 2001
From: MinRK <benjaminrk@gmail.com>
Date: Tue, 22 Oct 2013 09:54:28 -0700
Subject: [PATCH] don't warn when open_browser and not file_to_run

---
 IPython/html/notebookapp.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/IPython/html/notebookapp.py b/IPython/html/notebookapp.py
index 93cbe9f84..d6ec35829 100644
--- a/IPython/html/notebookapp.py
+++ b/IPython/html/notebookapp.py
@@ -738,7 +738,7 @@ class NotebookApp(BaseIPythonApplication):
             
             nbdir = os.path.abspath(self.notebook_manager.notebook_dir)
             f = self.file_to_run
-            if f.startswith(nbdir):
+            if f and f.startswith(nbdir):
                 f = f[len(nbdir):]
             else:
                 self.log.warn(