$ git clone -n https://src.fedoraproject.org/rpms/virtualbox-guest-additions.git /var/lib/mock/f39-build-2541513-61806/root/chroot_tmpdir/scmroot/virtualbox-guest-additions
Cloning into '/var/lib/mock/f39-build-2541513-61806/root/chroot_tmpdir/scmroot/virtualbox-guest-additions'...
$ git fetch origin 42ee14bdc0ba23e7427c1c52ff48664bd2f3b0db:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/virtualbox-guest-additions
 * [new ref]         42ee14bdc0ba23e7427c1c52ff48664bd2f3b0db -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 42ee14b Update to 7.0.14 (#2258642)