From 4a106ee9e1551fc12c9a767b660c6cdf7b5d9823 Mon Sep 17 00:00:00 2001
From: Barry Warsaw <barry@python.org>
Date: Tue, 13 Nov 2001 18:00:40 +0000
Subject: [PATCH] parsedate_tz(): If data is false, return None.  Fixes bug
 #478115, IndexError when a Date: field exists with an empty value.

---
 Lib/rfc822.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/rfc822.py b/Lib/rfc822.py
index 430e6372f0f..00199495885 100644
--- a/Lib/rfc822.py
+++ b/Lib/rfc822.py
@@ -858,6 +858,8 @@ def parsedate_tz(data):
 
     Accounts for military timezones.
     """
+    if not data:
+        return None
     data = data.split()
     if data[0][-1] in (',', '.') or data[0].lower() in _daynames:
         # There's a dayname here. Skip it