"QQmlEngine::setContextForObject(): Object already has a QQmlContext" when running auto tests

1   QQmlEngine::setContextForObject                                                                                                                                                                                                                  qqmlengine.cpp               1462 0x7ffff0ec8fd5 
2   QQmlEnginePrivate::singletonInstance<QJSValue>                                                                                                                                                                                                   qqmlengine.cpp               2389 0x7ffff0ed4475 
3   QQmlEnginePrivate::singletonInstance<QObject *>                                                                                                                                                                                                  qqmlengine_p.h               504  0x7ffff0c31a51 
4   QV4::QQmlContextWrapper::getPropertyAndBase                                                                                                                                                                                                      qv4qmlcontext.cpp            238  0x7ffff0c2a655 
5   QV4::QQmlContextWrapper::resolveQmlContextPropertyLookupGetter                                                                                                                                                                                   qv4qmlcontext.cpp            486  0x7ffff0c2d11b 
6   QV4::Moth::VME::interpret                                                                                                                                                                                                                        qv4vme_moth.cpp              629  0x7ffff0d86a9e 
7   QV4::Moth::VME::exec                                                                                                                                                                                                                             qv4vme_moth.cpp              507  0x7ffff0d80e62 
8   QV4::Function::call                                                                                                                                                                                                                              qv4function.cpp              70   0x7ffff0b61270 
9   QQmlJavaScriptExpression::evaluate                                                                                                                                                                                                               qqmljavascriptexpression.cpp 229  0x7ffff0f98fb2 
10  QQmlBinding::evaluate                                                                                                                                                                                                                            qqmlbinding.cpp              216  0x7ffff0e41646 
11  QQmlNonbindingBinding::doUpdate                                                                                                                                                                                                                  qqmlbinding.cpp              252  0x7ffff0e49de9 
12  QQmlBinding::update                                                                                                                                                                                                                              qqmlbinding.cpp              192  0x7ffff0e412e4 
13  QQmlBinding::setEnabled                                                                                                                                                                                                                          qqmlbinding.cpp              555  0x7ffff0e43f28 
14  QQmlObjectCreator::finalize                                                                                                                                                                                                                      qqmlobjectcreator.cpp        1417 0x7ffff10442c2 
15  QQmlComponentPrivate::complete                                                                                                                                                                                                                   qqmlcomponent.cpp            988  0x7ffff0e77907 
16  QQmlComponentPrivate::completeDeferred                                                                                                                                                                                                           qqmlcomponent.cpp            981  0x7ffff0e77749 
17  QtQuickPrivate::completeDeferred                                                                                                                                                                                                                 qquickdeferredexecute.cpp    150  0x7ffff1ce197e 
18  quickCompleteDeferred<QQuickItem>                                                                                                                                                                                                                qquickdeferredexecute_p_p.h  87   0x7ffff1c3af02 
19  QQuickControlPrivate::executeContentItem                                                                                                                                                                                                         qquickcontrol.cpp            735  0x7ffff1cd60d8 
20  QQuickControl::componentComplete                                                                                                                                                                                                                 qquickcontrol.cpp            1906 0x7ffff1cdab97 
21  QQuickAbstractButton::componentComplete                                                                                                                                                                                                          qquickabstractbutton.cpp     1028 0x7ffff1c333d7 
22  QQmlObjectCreator::finalize                                                                                                                                                                                                                      qqmlobjectcreator.cpp        1449 0x7ffff10448f2 
23  QQmlIncubatorPrivate::incubate                                                                                                                                                                                                                   qqmlincubator.cpp            364  0x7ffff0f8f82e 
24  QQmlEnginePrivate::incubate                                                                                                                                                                                                                      qqmlincubator.cpp            90   0x7ffff0f8d5e0 
25  QQmlComponentPrivate::incubateObject                                                                                                                                                                                                             qqmlcomponent.cpp            1224 0x7ffff0e7972a 
26  QQmlDelegateModelPrivate::object                                                                                                                                                                                                                 qqmldelegatemodel.cpp        1296 0x7fffed93037d 
27  QQmlDelegateModel::object                                                                                                                                                                                                                        qqmldelegatemodel.cpp        1337 0x7fffed930930 
28  QQuickItemViewPrivate::createItem                                                                                                                                                                                                                qquickitemview.cpp           2349 0x7fffef8d669c 
29  QQuickListViewPrivate::addVisibleItems                                                                                                                                                                                                           qquicklistview.cpp           717  0x7fffef90a393 
30  QQuickItemViewPrivate::refill                                                                                                                                                                                                                    qquickitemview.cpp           1801 0x7fffef8cf0b4 
31  QQuickItemViewPrivate::refill                                                                                                                                                                                                                    qquickitemview.cpp           1771 0x7fffef8ceb43 
32  QQuickItemView::componentComplete                                                                                                                                                                                                                qquickitemview.cpp           1496 0x7fffef8ca72e 
33  QQmlObjectCreator::finalize                                                                                                                                                                                                                      qqmlobjectcreator.cpp        1449 0x7ffff10448f2 
34  QQmlComponentPrivate::complete                                                                                                                                                                                                                   qqmlcomponent.cpp            988  0x7ffff0e77907 
35  QQmlComponentPrivate::completeDeferred                                                                                                                                                                                                           qqmlcomponent.cpp            981  0x7ffff0e77749 
36  QtQuickPrivate::completeDeferred                                                                                                                                                                                                                 qquickdeferredexecute.cpp    150  0x7ffff1ce197e 
37  quickCompleteDeferred<QQuickItem>                                                                                                                                                                                                                qquickdeferredexecute_p_p.h  87   0x7ffff1c3af02 
38  QQuickPopupItemPrivate::executeContentItem                                                                                                                                                                                                       qquickpopupitem.cpp          106  0x7ffff1dab616 
39  QQuickControl::componentComplete                                                                                                                                                                                                                 qquickcontrol.cpp            1906 0x7ffff1cdab97 
40  QQuickPane::componentComplete                                                                                                                                                                                                                    qquickpane.cpp               392  0x7ffff1d8b766 
41  QQuickPage::componentComplete                                                                                                                                                                                                                    qquickpage.cpp               453  0x7ffff1d857a4