profile search: unable to deselect multi-select field

create a profile for searching that includes a select or multi-select field. on the demo site I set one up using the marital status field, for example.

open the profile in search/listing mode.
select an option from the multi-select field and search.
re-open the search form and remove the previously selected option; run the search.

although the form indicates the field value is no longer being search, the result qill and results are still filtering by that previously selected value.