fill for multi types with None value

config.py

@@ -198,11 +198,12 @@ class Config(object):
             # special owners
             if owner in special_owners:
                 value = self._cfgimpl_values[name]
+                if value != None:
                     if opt_or_descr.is_multi():
                         if owner == 'fill' and None not in value:
                             return value
                     else:
-                    if owner == 'fill' and value != None:
+                        if owner == 'fill':
                             return value
                 result = special_owner_factory(name, owner, 
                             value=value,
@@ -220,6 +221,9 @@ class Config(object):
                         ' for option {0}'.format(name))
                 
                 if opt_or_descr.is_multi():
+                    if value == None:
+                        _result = [result]
+                    else:
                         _result = []
                         for val in value:
                             if val == None: