separate value in slave

tiramisu/setting.py

@@ -433,7 +433,8 @@ class Settings(object):
                             value=None, force_permissive=False,
                             force_properties=None,
                             setting_properties=undefined,
-                            self_properties=undefined):
+                            self_properties=undefined,
+                            index=None):
         """
         validation upon the properties related to `opt_or_descr`
 
@@ -480,7 +481,7 @@ class Settings(object):
         else:
             if 'mandatory' in properties and \
                     not self._getcontext().cfgimpl_get_values()._isempty(
-                        opt_or_descr, value):
+                        opt_or_descr, value, index=index):
                 properties.remove('mandatory')
             elif opt_or_descr.impl_is_multi() and \
                     not is_write and 'empty' in forced_properties and \