Always set partition's permission.

In case if something went wrong in previous run, one can have problem with
partition and its permission can be wrong.

slapos/recipe/erp5testnode/SlapOSControler.py

@@ -33,7 +33,7 @@ class SlapOSControler(object):
     partition_path = os.path.join(config['instance_root'], partition_reference)
     if not os.path.exists(partition_path):
       os.mkdir(partition_path)
-      os.chmod(partition_path, 0750)
+    os.chmod(partition_path, 0750)
     computer.updateConfiguration(xml_marshaller.dumps({
  'address': config['ipv4_address'],
  'instance_root': config['instance_root'],