$ git clone -n https://src.fedoraproject.org/rpms/libnbd.git /var/lib/mock/f40-build-2297792-56495/root/chroot_tmpdir/scmroot/libnbd
Cloning into '/var/lib/mock/f40-build-2297792-56495/root/chroot_tmpdir/scmroot/libnbd'...
$ git fetch origin 4d3f01730affd2862d4a409ea7e626ed9afaac9d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libnbd
 * [new ref]         4d3f01730affd2862d4a409ea7e626ed9afaac9d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4d3f017 New upstream development version 1.19.5