I'm currently thinking it's a bad idea to backpatch this but I'd consider it more if someone else thought it was a good idea or if more people came along complaining about poor plan choice in plans containing WindowAggs. Currently, it seems better not to destabilise plans in the back branches. (CC'd Tim, who reported #17862, as he may have an opinion on this)
I agree it's better not to destabilise plans in the back branches.
