Can't use input when model has no value

[w33ble]

Issue:

Angular injects a ? record as a default value in a select when using ng-options. This is accounted for when the model or options update (see here), but not when the directive is first loaded.

The result is that the ? record is selected by default, and you can't type in the input until you delete the selected value. This is a weird UI, as the user can see all the options available, and can use arrow keys to navigate, but can not type, even though the input is empty and there is a blinking cursor.

Demo:

http://plnkr.co/edit/pjsMFK?p=preview

This is the demo from the README, but with the default model value commented out.