From 38a33c54a657e68903e6ba73ae0509dbeca62b81 Mon Sep 17 00:00:00 2001
From: Jeroen Hoekx <jeroen.hoekx@hamok.be>
Date: Sat, 31 Mar 2012 13:58:15 +0200
Subject: [PATCH] Make copy module idempotent.

Check md5sum before overwriting a file. Unconditionally copying changes the timestamp.
---
 library/copy | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/library/copy b/library/copy
index dcb339d2746..fecfeeafacb 100755
--- a/library/copy
+++ b/library/copy
@@ -54,11 +54,10 @@ changed = False
 if os.path.exists(dest):
     md5sum = os.popen("md5sum %s" % dest).read().split()[0]
 
-os.system("cp %s %s" % (src, dest))
-
-md5sum2 = os.popen("md5sum %s" % dest).read().split()[0]
+md5sum2 = os.popen("md5sum %s" % src).read().split()[0]
 
 if md5sum != md5sum2:
+    os.system("cp %s %s" % (src, dest))
     changed = True
 
 # mission accomplished