Restore erased line

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@6512 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Constraint/__init__.py

@@ -5,4 +5,5 @@ from CategoryRelatedMembershipArity import CategoryRelatedMembershipArity
 from AttributeEquality import AttributeEquality
 from PropertyExistence import PropertyExistence
 from CategoryExistence import CategoryExistence
+from PortalTypeClass import PortalTypeClass
 from CategoryAcquiredMembershipArity import CategoryAcquiredMembershipArity