merge r16934 from branch 2.4 to trunk

bug 2705 fixed: if the rotation is "0", no rotation is needed, we skip the
rotate function which behaves badly (in ExtIM) with a zero degree rotation.



git-svn-id: http://piwigo.org/svn/trunk@16936 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/include/image.class.php

@@ -133,7 +133,7 @@ class pwg_image
 
     $this->image->resize($resize_dimensions['width'], $resize_dimensions['height']);
 
-    if (isset($rotation))
+    if (!empty($rotation))
     {
       $this->image->rotate($rotation);
     }