Fix Zope 2.12 breakages on testEditorField, along with commit #31588, as soon as the fix for https://bugs.launchpad.net/zope2/+bug/246983 is applied on Zope 2.12

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@31589 20353a03-c40f-0410-a6d1-a30d3c3de9de