ng-options group by duplication (1.4.8)

[m3fawner]

 <select ng-model="ctrl.model" ng-options="reason.description group by reason.type for reason in ctrl.possibleReasons"></select>

With a collection of:

this.possibleReasons = [{ type : 1, description: 'Test1'}, { type: 2, description: 'Test2'}];

produces a dom element that has 4 opt-groups output instead of the expected two. This creates a duplication of the groups within the select element.

[gkalpak]

Duplicate of #13487.

It has already been fixed in master. The fix will land with v1.4.9 and v1.5.0-rc.1.