Clear value when it is no longer available in the option list

[Zelarith]

Feature request :
If a selected option becomes unavailable, it should be automatically deselected.

That's how it works with a regular "select" : let's say I have a list of 2 values available :
option 1
option 2

By modifying another value in my form, this list of options becomes :
option 2
option 3

If I had option 2 selected, it will still be selected, as it has remained available all along.
If I had option 1 selected, it will be automatically deselected, as it is not a valid value anymore

In ui-select, the auto deselection never happens, so I have to handle it myself.

Versions used :
Angular 1.5.9
UI-Select 0.19.8