From 283042c675e4c641dbaf0c40ad872f0d7a2cec87 Mon Sep 17 00:00:00 2001
From: Thomas Kluyver <thomas@kluyver.me.uk>
Date: Sun, 4 Dec 2016 14:33:39 +0000
Subject: [PATCH] Ensure variable is set if exc_info is falsey

Closes gh-1940
---
 notebook/base/handlers.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/notebook/base/handlers.py b/notebook/base/handlers.py
index dcabc4cb3..4a081afac 100755
--- a/notebook/base/handlers.py
+++ b/notebook/base/handlers.py
@@ -359,6 +359,7 @@ class IPythonHandler(AuthenticatedHandler):
         exc_info = kwargs.get('exc_info')
         message = ''
         status_message = responses.get(status_code, 'Unknown HTTP Error')
+        exception = '(unknown)'
         if exc_info:
             exception = exc_info[1]
             # get the custom message, if defined