$ git clone -n https://src.fedoraproject.org/rpms/xfdesktop.git /var/lib/mock/f42-build-3384255-45084/root/chroot_tmpdir/scmroot/xfdesktop
Cloning into '/var/lib/mock/f42-build-3384255-45084/root/chroot_tmpdir/scmroot/xfdesktop'...
$ git fetch origin abeefd8f35f648d2125065498cd671d7a8f83736:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xfdesktop
 * [new ref]         abeefd8f35f648d2125065498cd671d7a8f83736 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at abeefd8 Update to 4.20.1 (fixes rhbz#2346086 )