Availability report ignores global option "Dropdown first entry"

Even if we select "None" for "Dropdown first entry" global option, on the Availability report "Host group" and "Host" will have "not selected" but actually report works as for "All"

I.e. we see statistic of all hosts from all groups and it's critical problem on big installations.

Reproduced for latest 1.8 and 2.0.