AngularJs radio buttons are connected when using ng-form with ng-repeat - forms

Question

See this plnkr http://plnkr.co/edit/WZHMuYY3y2wbI6UysvY6?p=preview
When using a ng-form tag on an ng-repeat which contains a radio button group, the radio buttons are linked so if you check a radio button in one ng-repeat it will deselect in all the other ng-repeats. This puzzles me as the model of the ng-repeat is otherwise isolated from the other items. This is not only an issue when using ng-repeat. It also occurs when having multiple instances of a custom directive with isolated scope which renders a
<div ng-form name="myForm">
In the Plnkkr try adding a number of items and check the radio buttons on some of the items.
They should be independent, but they are not.
Is this a bug in Angular?
If not why does it work this way and how can I work around it?
<form name="mainForm" ng-submit="submitAll()">
<ul>
<li ng-repeat="item in items" ng-form="subForm">
<input type="text" required name="name" ng-model="item.name"/>
<input type="radio" name="myRadio" value="r1" ng-model="item.radio" /> r1
<input type="radio" name="myRadio" value="r2" ng-model="item.radio" /> r2
<span ng-show="subForm.name.$error.required">required</span>
<button type="button" ng-disabled="subForm.$invalid" ng-click="submitOne(item)">Submit One</button>
</li>
</ul>
<button type="submit" ng-disabled="mainForm.$invalid">Submit All</button>
</form>

Answer 1

Those radio buttons are "connected" by a browser since you are giving them the same name. Just drop the name attribute and things start to work as expected:
http://plnkr.co/edit/AEtGstSBV6oydtvds52Y?p=preview

Answer 2

As per your last comment, I have tried this out and it works. I'm not using the built-in angular validation but I believe it works all the same and is very simple
<li ng-repeat="item in items" ng-form="subForm">
<input type="text" required name="name" ng-model="item.name"/>
<input type="radio" value="r1" ng-model="item.radio" /> r1
<input type="radio" value="r2" ng-model="item.radio" /> r2
<span ng-show="item.radio==''">required</span>
<button type="button" ng-disabled="subForm.$invalid || item.radio==''" ng-click="submitOne(item) ">Submit One</button>
</li>
See my working example at http://wiredbeast.com/coolframework/stackover.html
The trick is using ng-show="item.radio==''" to show the validation error and to disable the "Submit One" button.
In my honest opinion angular form validation and browser validation with checkboxes and radios is not very solid.