Ticket #4878: attributes.js-r6333-patch.txt

101c101,103
<                               var values = jQuery.makeArray(value);
---
>                               var values = jQuery.makeArray(value),
>                                       one = this.type == "select-one",
>                                       canSelect = true;
104c106
<                                       this.selected = (jQuery.inArray( this.value, values ) >= 0 ||
---
>                                       this.selected = canSelect && (jQuery.inArray( this.value, values ) >= 0 ||
105a108,109
>                                       if (this.selected && one)
>                                               canSelect = false;