Fix (r3) a regression in flip iop legacy params handling

Basic Idea: if history stack has flip iop with orientation != -1,
then this history stack was, either:
1) created before regression (and had gone through legacy_params, which never produces -1), and we need to fix it!
or
2) created after regression (by manual changes to flip iop, and we should not fix it

Q: Is there a way to differentiate between these two?