Fix typo.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@10199 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Constraint/CategoryMembershipArity.py

@@ -64,7 +64,7 @@ class CategoryMembershipArity(Constraint):
                                                  portal_type=portal_type))
     if (arity < min_arity) or (arity > max_arity):
       # Generate error message
-      error_message = "Arrity error for relation '%s'" % \
+      error_message = "Arity error for relation '%s'" % \
                       base_category
       if portal_type is not ():
         error_message += " and portal_type: '%s'" % str(portal_type)