From 4f738fd8cf2342585f2e0b0e5c8989b737aea75d Mon Sep 17 00:00:00 2001
From: Damien Elmes <git@ichi2.net>
Date: Fri, 24 May 2013 13:56:50 +0900
Subject: [PATCH] don't die if appdata not defined

---
 aqt/upgrade.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/aqt/upgrade.py b/aqt/upgrade.py
index 1b904ede4..f9459a398 100644
--- a/aqt/upgrade.py
+++ b/aqt/upgrade.py
@@ -18,7 +18,7 @@ class Upgrader(object):
     def maybeUpgrade(self):
         p = self._oldConfigPath()
         # does an old config file exist?
-        if not os.path.exists(p):
+        if not p or not os.path.exists(p):
             return
         # load old settings and copy over
         try:
@@ -38,7 +38,11 @@ to import your decks from previous Anki versions."""))
 
     def _oldConfigPath(self):
         if isWin:
-            os.environ['HOME'] = os.environ['APPDATA']
+            try:
+                os.environ['HOME'] = os.environ['APPDATA']
+            except:
+                # system with %APPDATA% not defined
+                return None
             p = "~/.anki/config.db"
         elif isMac:
             p = "~/Library/Application Support/Anki/config.db"