Select ng-options is dont reset with '<input type="reset"> '

[fovotz]

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

What is the current behavior?
When I have a select with ng-options with an array with objects, the behavior is weird when I reset the form by clicking in a <input type="reset" value="clear">

The problem occurs because when you select an option angular put a attribute selected="selected" on the option and never clears the attribute in the others options.

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).

Chosse different options in the select and then press the reset button.

You can watch the error here: https://plnkr.co/edit/Epq5fVrS0I6p2csrntli?p=preview

What is the expected behavior?
The standard reset form button works properly

What is the motivation / use case for changing the behavior?
The standard reset form button doesn't works properly when ng-options is used with a array with objects.

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.
1.5.5, 1.5.7

Other information (e.g. stacktraces, related issues, suggestions how to fix)
The partial solution of this issue is commenting the line of the angular.js 1.5.5

28012 // option.element.setAttribute('selected', 'selected');

[gkalpak]

Wow! This seems to have been broken since 1.4.0-beta.6 (diff) - possibly by 6a03ca2.
(I wonder how come nobody reported it until now 😕 )

[Narretz]

Might be related to #14419

[Narretz]

Strange that his happens only with track by, though.
Because when you have track by, we are watching the track by expression, and that means when you select an option in a select with track by, the select will react to the model value change and call again the $render function with adds the selected attribute. This does not happen without track by.

So when the user selects an option, neither the browser nor we add the selected attribute. It is only added when the the model changes (for single selects)

Also note that we are actually interested in what happens when we set the model to {}. The reset button is irrelevant to the issue.