$ git clone -n https://src.fedoraproject.org/rpms/rust-rand0.8.git /var/lib/mock/f42-build-3251786-41222/root/chroot_tmpdir/scmroot/rust-rand0.8
Cloning into '/var/lib/mock/f42-build-3251786-41222/root/chroot_tmpdir/scmroot/rust-rand0.8'...
$ git fetch origin afbd05e1031782b55eab3953c02dc4becdc0a472:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rand0.8
 * [new ref]         afbd05e1031782b55eab3953c02dc4becdc0a472 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at afbd05e Initial import (rand 0.8 compat package)