matrix: use booleans for booleans (TBD ifaces)

product/ERP5Type/mixin/matrix.py

@@ -96,16 +96,16 @@ class Matrix(object):
     aq_self = aq_base(self)
 
     if getattr(aq_self, 'index', None) is None:
-      return 0
+      return False
 
     if base_id not in self.index:
-      return 0
+      return False
 
     for i in self.getCellIds(base_id=base_id):
       if hasattr(self, i): # We should try to use aq_self if possible but XXX
-        return 1
+        return True
 
-    return 0
+    return False
 
   security.declareProtected( Permissions.AccessContentsInformation,
                              'hasInRange' )