GridLayout: Sometimes segmentation fault on destruction

Using the test case included in gridinstack.tar.gz

1 - click the red button to push the page (MyPage.qml using GridLayout) in the stack
2 - press the green button to go back
=> There is a segfault when trying the destroy the MyPage.qml

Note that in MyPage.qml, the segfault does not arise if:

• you comment out the line "property int myproperty: 0"
• or if you comment the line "Layout.columnSpan: 2" in label2
  (commenting the same line in label1 does not prevent the segfault)