failing test for record not unloaded when a payload is returned

It seems common for APIs to return a paylaod when deleting a record.
Although there is a test for when `undefined` is returned from
`deleteRecord` in the adapter here: https://github.com/emberjs/data/blob/master/tests/integration/records/delete-record-test.js#L87

There are currently no tests showing what happens when you return a
payload. It seems like the correct behavior for destroyRecord should be
`deleteRecord` + `save` + `unloadRecord`.

tests/integration/records/delete-record-test.js

@@ -139,6 +139,77 @@ test('deleting a record that is part of a hasMany removes it from the hasMany re
   assert.equal(group.get('people.length'), 1, 'expected 1 related records after delete');
 });
 
+test('deleting a record that is part of a hasMany removes it from the hasMany recordArray when adapter deleteRecord function returns a payload', function(assert) {
+  let group;
+  let person;
+  const Group = DS.Model.extend({
+    people: DS.hasMany('person', { inverse: null, async: false })
+  });
+  Group.toString = () => { return 'Group'; }
+
+  env.adapter.deleteRecord = function() {
+    return EmberPromise.resolve({
+      data: {
+        id: '1',
+        type: 'group',
+        attributes: {}
+      }
+    });
+  };
+
+  env.registry.register('model:group', Group);
+
+  run(function() {
+    env.store.push({
+      data: {
+        type: 'group',
+        id: '1',
+        relationships: {
+          people: {
+            data: [
+              { type: 'person', id: '1' },
+              { type: 'person', id: '2' }
+            ]
+          }
+        }
+      },
+      included: [
+        {
+          type: 'person',
+          id: '1',
+          attributes: {
+            name: 'Adam Sunderland'
+          }
+        },
+        {
+          type: 'person',
+          id: '2',
+          attributes: {
+            name: 'Dave Sunderland'
+          }
+        }
+      ]
+    });
+
+    group = env.store.peekRecord('group', '1');
+    person = env.store.peekRecord('person', '1');
+  });
+
+  // Sanity Check we are in the correct state.
+  assert.equal(group.get('people.length'), 2, 'expected 2 related records before delete');
+  assert.equal(person.get('name'), 'Adam Sunderland', 'expected related records to be loaded');
+
+  const promise = run(() => group.destroyRecord());
+
+  return promise.then(() => {
+    // qunit complains if i pass the record to QUnit due to some assertion in ember
+    // iterating over the properties.
+    const hasGroup = env.store.peekRecord('group', '1') ? true : false;
+    assert.equal(hasGroup, false);
+    assert.equal(person.get('group'), null, 'expected relationship to be null');
+  });
+});
+
 test('records can be deleted during record array enumeration', function(assert) {
   var adam, dave;