$ git clone -n https://src.fedoraproject.org/rpms/grub2.git /var/lib/mock/f40-build-2066890-49285/root/chroot_tmpdir/scmroot/grub2
Cloning into '/var/lib/mock/f40-build-2066890-49285/root/chroot_tmpdir/scmroot/grub2'...
$ git fetch origin 4562b72afc296be6d0a9fa16d8b0e5729d32cca0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/grub2
 * [new ref]         4562b72afc296be6d0a9fa16d8b0e5729d32cca0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4562b72 chainloader: remove device path debug message