hasMany can update if you push values

adapters.application.js

import DS from 'ember-data';

export default DS.JSONAPIAdapter.extend({
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddles', 
  thingIds: Ember.computed.mapBy('model.things', 'id'),
  thingState: Ember.computed.mapBy('model.things', 'isDeleted')
});

models.person.js

import Ember from 'ember';
import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  name: attr('string'),
  things: hasMany('thing')
});

models.thing.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  person: belongsTo('person')
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  beforeModel() {
    let data = {
      data: {
        id: 1,
       	type: 'person', 
        relationships: {
          things: { 
            data: [
            ]
          }
        }
      },
      included: [
        {id: 1, type: "thing"},
        {id: 2, type: "thing"}
      ]
    };
    this.store.pushPayload(data);
  },
  
  model() {
   let person = this.store.peekRecord('person', 1);
   let things = this.store.peekAll('thing');
   let [thing] = things.toArray();
   
   // set 2 thing on the person to put 
   person.set('things', things);
   
   // or this also shows same behaviour  
   // person.get('things').pushObject(thing);
   
   let data = { 
     id: 1,
     type: 'person', 
     relationships: {
       things: { 
         data: [ 
           {id: 2, type: "thing"}
         ]
       }
     }
    };  
    
    // this will add one thing to the things a person has
    this.store.pushPayload({data});
    
    return person;
  }
});

templates.application.hbs

<h3>Welcome to Bug where pushPaylod does not clear hasMany relationship</h3>

<br>
My things ids:{{thingIds}}
<br>
I should have 1 things and I have:{{model.things.length}}
<br>
Person state: {{model.currentState.stateName}}
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.11.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "mockjax": "https://cdnjs.cloudflare.com/ajax/libs/jquery-mockjax/1.6.2/jquery.mockjax.js",
    "ember": "2.10.2",
    "ember-data": "release",
    "ember-template-compiler": "2.10.2",
    "ember-testing": "2.10.2"
  },
  "addons": {}
}