fixed bug #719514 ' Themes: <file> and <otherfile> are the same file'

Fixes: https://launchpad.net/bugs/719514

openlp/core/ui/thememanager.py

@@ -698,7 +698,7 @@ class ThemeManager(QtGui.QWidget):
         finally:
             if out_file:
                 out_file.close()
-        if image_from and image_from != image_to:
+        if image_from and os.path.abspath(image_from) != os.path.abspath(image_to):
             try:
                 encoding = get_filesystem_encoding()
                 shutil.copyfile(