$ git clone -n https://src.fedoraproject.org/rpms/rust-tower-layer.git /var/lib/mock/f39-build-1455734-32919/root/chroot_tmpdir/scmroot/rust-tower-layer
Cloning into '/var/lib/mock/f39-build-1455734-32919/root/chroot_tmpdir/scmroot/rust-tower-layer'...
$ git fetch origin 6a51736758e4e8129963f4521e18202bfb79e3e9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tower-layer
 * [new ref]         6a51736758e4e8129963f4521e18202bfb79e3e9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6a51736 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild