$ git clone -n https://src.fedoraproject.org/rpms/rust-below-dump.git /var/lib/mock/f40-build-1538257-23931/root/chroot_tmpdir/scmroot/rust-below-dump
Cloning into '/var/lib/mock/f40-build-1538257-23931/root/chroot_tmpdir/scmroot/rust-below-dump'...
$ git fetch origin bb7510fb97fbaeaf5f2aa62dd05cece384fdc9b1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-below-dump
 * [new ref]         bb7510fb97fbaeaf5f2aa62dd05cece384fdc9b1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bb7510f Update to 0.8.1 (rhbz#2272251)