Mike Boylan on Twitter points to this new Apple Support article on re-installing your Mac. The option for restoring from internet recovery have changed:
Command-R:
Reinstall the latest macOS that was installed on your Mac, without upgrading to a later version.1
Option-Command-R:
Upgrade to the latest macOS that is compatible with your Mac.2
Shift-Option-Command-R:
Requires macOS Sierra 10.12.4 or later. Reinstall the macOS that came with your Mac, or the version closest to it that is still available.