Apple removed the checkbox from the installer – on APFS capable hardware. The one that allowed us to skip the APFS conversion, but a new environment variable added to the latest installer script should work around this. And in case that’s still not enough…
I wrote a new handy script (checkAPFSSettings.sh) to check the APFS conversion settings in four files in the macOS Install Data folder.
It will print out the current values, and then (try to) change them to false. Just to be sure that the APFS conversion won’t be done. That is. In case you are not able to use APFS with a legacy boot loader (think Chameleon and RevoBoot).
You must run the script with sudo, or nothing will change. Run it once, and then once again to check the values.
Please note that you have to run the installer first. Then reboot into another installation (or single user mode) and run checkAPFSSettings.sh to verify if all settings are set to false.
This way you won’t be surprised… like I was when I installed the latest Developer Preview.
On a hack. Just don’t set the APFS support bit (think firmware features).