$ git clone -n https://src.fedoraproject.org/rpms/rust-uu_base64.git /var/lib/mock/f40-build-781150-131430/root/chroot_tmpdir/scmroot/rust-uu_base64
Cloning into '/var/lib/mock/f40-build-781150-131430/root/chroot_tmpdir/scmroot/rust-uu_base64'...
$ git fetch origin 2dfc25f8438cd3c876efced3b2c47f00e5435f7a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-uu_base64
 * [new ref]         2dfc25f8438cd3c876efced3b2c47f00e5435f7a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2dfc25f Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild