From 852be48cb73e3299a48c4cc646a3fbf30313606f Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 3 May 2017 16:45:59 +0530
Subject: [PATCH] ...

---
 src/calibre/utils/test_lock.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/utils/test_lock.py b/src/calibre/utils/test_lock.py
index 08c4c8849d..59eaa1874e 100644
--- a/src/calibre/utils/test_lock.py
+++ b/src/calibre/utils/test_lock.py
@@ -39,7 +39,7 @@ def run_worker(mod, func, **kw):
     if iswindows:
         import win32process
         kw['creationflags'] = win32process.CREATE_NO_WINDOW
-    kw['env'] = env
+    kw['env'] = {str(k):str(v) for k, v in env.iteritems()}  # windows needs bytes in env
     return subprocess.Popen(exe, **kw)