$ git clone -n https://src.fedoraproject.org/rpms/prooftree.git /var/lib/mock/f40-build-2134949-50815/root/chroot_tmpdir/scmroot/prooftree
Cloning into '/var/lib/mock/f40-build-2134949-50815/root/chroot_tmpdir/scmroot/prooftree'...
$ git fetch origin b243f9bb3e9a68d4223c99611334384faf35ae75:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/prooftree
 * [new ref]         b243f9bb3e9a68d4223c99611334384faf35ae75 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b243f9b OCaml 5.1.1 + s390x code gen fix for Fedora 40