<existing_search_string> OPERATOR (portal_type:value1 OR portal_type:value2)

rather than as before:

<existing_search_string> portal_type:value1 OR portal_type:value2

which have a totally different meaning and generates a wrong query.
Make sure that OPERATOR is configurable (default='AND')

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@38402 20353a03-c40f-0410-a6d1-a30d3c3de9de