Comment 1 for bug 902356

The crash is in test_if_skip_sort_order() in the line:

             if (used_key_parts > used_index_parts)
               used_pk_parts= used_key_parts-used_index_parts;
             rec_per_key= keyinfo->rec_per_key[used_key_parts-1];

where used_key_parts == 0, which results in an access to
keyinfo->rec_per_key[-1]