$ git clone -n https://src.fedoraproject.org/rpms/rust-cargo.git /var/lib/mock/f41-build-side-1-2923658-34982/root/chroot_tmpdir/scmroot/rust-cargo
Cloning into '/var/lib/mock/f41-build-side-1-2923658-34982/root/chroot_tmpdir/scmroot/rust-cargo'...
$ git fetch origin 5541f299e47ab9c1d69be8aadb0a5bddfadc31d5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cargo
 * [new ref]         5541f299e47ab9c1d69be8aadb0a5bddfadc31d5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5541f29 Bump base64 from 0.21 to 0.22 and itertools from 0.12 to 0.13