$ git clone -n https://src.fedoraproject.org/rpms/virtualbox-guest-additions.git /var/lib/mock/f42-bootstrap-3462993-45594/root/chroot_tmpdir/scmroot/virtualbox-guest-additions
Cloning into '/var/lib/mock/f42-bootstrap-3462993-45594/root/chroot_tmpdir/scmroot/virtualbox-guest-additions'...
$ git fetch origin f881eeb1cf194f30525f55be941da8493c45239a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/virtualbox-guest-additions
 * [new ref]         f881eeb1cf194f30525f55be941da8493c45239a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f881eeb Update virtualbox-guest-additions to 7.1.6 (#2339180)