$ git clone -n https://src.fedoraproject.org/rpms/rust-uu_head.git /var/lib/mock/f40-build-1906037-25074/root/chroot_tmpdir/scmroot/rust-uu_head
Cloning into '/var/lib/mock/f40-build-1906037-25074/root/chroot_tmpdir/scmroot/rust-uu_head'...
$ git fetch origin b2a8d69102a899deca41846eac15b7024e90c744:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-uu_head
 * [new ref]         b2a8d69102a899deca41846eac15b7024e90c744 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b2a8d69 Update to version 0.0.27; Fixes: RHBZ#2260217