$ git clone -n https://src.fedoraproject.org/rpms/rust-rand_core0.6.git /var/lib/mock/f45-build-44235-811/root/chroot_tmpdir/scmroot/rust-rand_core0.6
Cloning into '/var/lib/mock/f45-build-44235-811/root/chroot_tmpdir/scmroot/rust-rand_core0.6'...
$ git fetch origin d3d7d65abaef00f63b330f66c74ad7d9b28aaa64:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rand_core0.6
 * [new ref]         d3d7d65abaef00f63b330f66c74ad7d9b28aaa64 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d3d7d65 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild