Run git bisect:
> git bisect start
> git bisect good 72a72315b052180a7df90a26000fdca4ef09dd94
> git bisect bad f2bb57c19455e77fd71be782f9ee9092f31bd2a9
> git bisect run /tmp/check-kaleidoscope-ch4.sh
...
ready> ready> Evaluated to 5.000000
ready> ready> + exit_code=0