Do you want to request a feature or report a bug?
Bug.

What is the current behavior?
In 1.5.6 an html <option> with ngSelected seems to have the selected attribute applied, but that option won't highlight. Tried with Chrome.
This happen when using ngSelected in combination with ngRepeat; if used in static <option> elements it works fine.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://plnkr.co or similar (template: http://plnkr.co/edit/tpl:yBpEi4).

Example code:

<select ng-model="user.item_id">
      <option ng-selected="i.id == user.item_id" ng-repeat="i in items" value={{i.id}}>
        {{i.name}}
      </option>
</select>

Plunker: https://plnkr.co/edit/7oi4KwzMhGi3kdltSklg?p=preview

What is the expected behavior?
The option should actually get highlighted - like it worked until 1.3.20

Plunker to the working version: https://plnkr.co/edit/0ApQeZ6Kar2yQisELXfT?p=preview

What is the motivation / use case for changing the behavior?
n\a

Which versions of Angular, and which browser / OS are affected by this issue? Did this work in previous versions of Angular? Please also test with the latest stable and snapshot (https://code.angularjs.org/snapshot/) versions.

Chrome 51.0.2704.103 m
Win 7 Ultimate 64 bit

Other information (e.g. stacktraces, related issues, suggestions how to fix)
n\a