$ git clone -n https://src.fedoraproject.org/rpms/zimg.git /var/lib/mock/f40-build-2046616-48888/root/chroot_tmpdir/scmroot/zimg
Cloning into '/var/lib/mock/f40-build-2046616-48888/root/chroot_tmpdir/scmroot/zimg'...
$ git fetch origin 4777c3ad68850e9b4f318d2a75867bce7d5f9967:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/zimg
 * [new ref]         4777c3ad68850e9b4f318d2a75867bce7d5f9967 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4777c3a Update to 3.0.5