Fix parent handling in _on_rows_removed/inserted
Fix parent handling in _on_rows_removed/inserted

With Qt4, we get invalid parents (as a root element changed) for both
'parent' (rows{Inserted,Removed} argument) and 'c.parent'
(rowsAboutToBe{Inserted,Removed} argument). Both represent the same
thing, but they don't compare equal using ==.

pytest-dev/pytest-qt,The-Compiler/pytest-qt