From 67e82c25e145cb0bc754db033d4963a5eba1360a Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 22 Dec 2015 09:33:54 +0530
Subject: [PATCH] Image compression: Fix spurious zero byte .bak files being
 created when compressing png images inside epub files

Works around bug in optipng
---
 src/calibre/utils/img.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/calibre/utils/img.py b/src/calibre/utils/img.py
index 99944d2ce9..8fb7389653 100644
--- a/src/calibre/utils/img.py
+++ b/src/calibre/utils/img.py
@@ -125,6 +125,11 @@ def run_optimizer(file_path, cmd, as_filter=False, input_data=None):
         except EnvironmentError as err:
             if err.errno != errno.ENOENT:
                 raise
+        try:
+            os.remove(outfile + '.bak')  # optipng creates these files
+        except EnvironmentError as err:
+            if err.errno != errno.ENOENT:
+                raise
 
 def optimize_jpeg(file_path):
     exe = get_exe_path('jpegtran')