switch to shutil.copy rather than os.system(cp)

copy

@@ -21,6 +21,7 @@
 import sys
 import os
 import shlex
+import shutil
 import syslog
 
 # ===========================================
@@ -85,10 +86,16 @@ if os.path.exists(dest):
     md5sum_dest = md5_sum(dest)
 else:
     if not os.access(os.path.dirname(dest), os.W_OK):
-        exit_kv(rc=1, failed=1, msg="Destination %s not writable" % (dest))
+        exit_kv(rc=1, failed=1, msg="Destination %s not writable" % (os.path.dirname(dest)))
 
 if md5sum_src != md5sum_dest:
-    os.system("cp %s %s" % (src, dest))
+    # was os.system("cp %s %s" % (src, dest))
+    try:
+        shutil.copyfile(src, dest)
+    except shutil.Error:
+        exit_kv(rc=1, failed=1, msg="failed to copy: %s and %s are the same" % (src, dest)) 
+    except IOError:
+        exit_kv(rc=1, failed=1, msg="failed to copy: %s to %s" % (src, dest)) 
     changed = True
 else:
     changed = False