$ git clone -n https://src.fedoraproject.org/rpms/rust-num-bigint-dig.git /var/lib/mock/f39-build-2298918-56517/root/chroot_tmpdir/scmroot/rust-num-bigint-dig
Cloning into '/var/lib/mock/f39-build-2298918-56517/root/chroot_tmpdir/scmroot/rust-num-bigint-dig'...
$ git fetch origin 39ae12dafbe8cc0f4b3a7f5c2f5b7b515d5178f0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-num-bigint-dig
 * [new ref]         39ae12dafbe8cc0f4b3a7f5c2f5b7b515d5178f0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 39ae12d Update to 0.8.4