$ git clone -n https://src.fedoraproject.org/rpms/rust-rsa.git /var/lib/mock/f40-build-2716149-72576/root/chroot_tmpdir/scmroot/rust-rsa
Cloning into '/var/lib/mock/f40-build-2716149-72576/root/chroot_tmpdir/scmroot/rust-rsa'...
$ git fetch origin b84fac4ac2353674e4fac0bec6facce437b4e34b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rsa
 * [new ref]         b84fac4ac2353674e4fac0bec6facce437b4e34b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b84fac4 Upload source