getMatchedUsers doesn't work as expected when using more than one filters

In the new Users administration UI, when filtering by both first name and last name, and the resultset should be empty, actually only one filter is taken into account.

For example, create two users, one with "2" on all the fields, and one with "3" on all fields, open the user administration tab, and write "2" in the "First name" filter, and "3" in the "Last name" filter. The user with "3" on all fields will be displayed, even though his first name is not "2".