Steps:
1. Open attached project
2. Open SampleScene
3. Unparent Child1
4. Drag Child2 onto Root
5. Drag Child1 onto Root
6. Drag Child1 between Child3 and Child2
7. Unparent Child1
8. Drag Child3 onto Root
9. Drag Child1 between Child3 and Child2
10. Press Undo 5 times
==>
Assertion failed on expression: 'm_TransformData.index == nextIndex'
Assertion failed on expression: 'nextIndex == -1'

Take a look into attached movie for details