The compilation error is fixed, but there is an UI/app related issue that prevents it from changing any option in firmware. See my comment here:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/issues/67
Instructions:
Using git you can check out that particular version by:
git checkout fd7cdada9d89cf6102c731a70157ec66145f643a
then compile the firmware again by
./build.sh ospi
and reboot.