$ git clone -n https://src.fedoraproject.org/rpms/rust-rustc_version.git /var/lib/mock/f40-build-2039279-48254/root/chroot_tmpdir/scmroot/rust-rustc_version
Cloning into '/var/lib/mock/f40-build-2039279-48254/root/chroot_tmpdir/scmroot/rust-rustc_version'...
$ git fetch origin 3ef2096e71fb2cf81558395076406661f12ecd6f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rustc_version
 * [new ref]         3ef2096e71fb2cf81558395076406661f12ecd6f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3ef2096 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild