506786 Index maintenance mechanism causes wrong search results when
    modifying attributes with subtypes
    
    Andrey Ivanov (andrey.ivanov@polytechnique.fr) pointed out my previous
    check-in for bug 506786 had an inefficient code.  To determine whether
    to delete an equality index key or not, the code checks the key still
    exists in the value array having the same attribute type.  The check
    should be done as soon as one value is found in the value array instead
    of checking through all of them.